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Title	Author	Year	Journal/Proceedings	Reftype	Export
Rapid blood flow computation on digital subtraction angiography: Preliminary results	Bourantas, G., Joldes, G.R., Katsanos, K., Kagadis, G.C., Wittek, A. and Miller, K.	2019	Nash, M., Nielsen, P.M.F., Wittek, A. and Miller, K. (Eds), Computational Biomechanics for Medicine 2018, Springer Nature, (Accepted)	bookchapter	[BibTeX]
BibTeX: @bookchapter{2019bourantasmillerrapid, author = {Bourantas, G and Joldes, G. R. and Katsanos, K. and Kagadis, G. C. and Wittek, A. and Miller, K.}, title = {Rapid blood flow computation on digital subtraction angiography: Preliminary results}, booktitle = {Computational Biomechanics for Medicine 2018}, publisher = {Springer Nature}, year = {2019}, note = {(Accepted)} }
An explicit meshless point collocation method for electrically driven magnetohydrodynamics (MHD) flow [Abstract]	Bourantas, G., Loukopoulos, V., Joldes, G., Wittek, A. and Miller, K.	2019	Applied Mathematics and Computation, vol. 348, pp. 215-233	article	[BibTeX] [PDF] [DOI]
Abstract: In this paper, we develop a meshless collocation scheme for the numerical solution of magnetohydrodynamics (MHD) flow equations. We consider the transient laminar flow of an incompressible, viscous and electrically conducting fluid in a rectangular duct. The flow is driven by the current produced by electrodes placed on the walls of the duct. The method combines a meshless collocation scheme with the newly developed Discretization Corrected Particle Strength Exchange (DC PSE) interpolation method. To highlight the applicability of the method, we discretize the spatial domain by using uniformly (Cartesian) and irregularly distributed nodes. The proposed solution method can handle high Hartmann (Ha) numbers and captures the boundary layers formed in such cases, without the presence of unwanted oscillations, by employing a local mesh refinement procedure close to the boundaries. The use of local refinement reduces the computational cost. We apply an explicit time integration scheme and we compute the critical time step that ensures stability through the Gershgorin theorem. Finally, we present numerical results obtained using different orientation of the applied magnetic field.
BibTeX: @article{2019maybourantasmillerAMaCexplicit, author = {G.C. Bourantas and V.C. Loukopoulos and G.R. Joldes and A. Wittek and K. Miller}, title = {An explicit meshless point collocation method for electrically driven magnetohydrodynamics (MHD) flow}, journal = {Applied Mathematics and Computation}, year = {2019}, volume = {348}, pages = {215--233}, doi = {10.1016/j.amc.2018.11.054} }
A Flux-Conservative Finite Difference Scheme for the Numerical Solution of the Nonlinear Bioheat Equation [Abstract]	Bourantas, G.C., Joldes, G.R., Wittek, A. and Miller, K.	2019	Nielsen, P.M.F., Wittek, A., Miller, K., Doyle, B., Joldes, G.R. and Nash, M.P. (Eds), Computational Biomechanics for Medicine: Measurements, Models, and Predictions, pp. 69-81, Springer International Publishing, Cham	bookchapter	[BibTeX] [DOI]
Abstract: We present a flux-conservative finite difference (FCFD) scheme for solving the nonlinear (bio)heat transfer in living tissue. The proposed scheme deals with steep gradients in the material properties for malignant and healthy tissues. The method applies directly on the raw medical image data without the need for sophisticated image analysis algorithms to define the interface between tumor and healthy tissues.
BibTeX: @bookchapter{2019bourantasmillerflux, author = {Bourantas, George C. and Joldes, Grand R. and Wittek, Adam and Miller, Karol}, title = {A Flux-Conservative Finite Difference Scheme for the Numerical Solution of the Nonlinear Bioheat Equation}, booktitle = {Computational Biomechanics for Medicine: Measurements, Models, and Predictions}, publisher = {Springer International Publishing}, year = {2019}, pages = {69--81}, doi = {10.1007/978-3-319-75589-2_7} }
A Discrete Element Method for Modelling Cell Mechanics: Application to the Simulation of Chondrocyte Behavior in the Growth Plate [Abstract]	Joldes, G.R., Bourantas, G.C., Wittek, A., Miller, K., Smith, D.W. and Gardiner, B.S.	2019	Nielsen, P.M.F., Wittek, A., Miller, K., Doyle, B., Joldes, G.R. and Nash, M.P. (Eds), Computational Biomechanics for Medicine: Measurements, Models, and Predictions, pp. 93-103, Springer International Publishing, Cham	bookchapter	[BibTeX] [DOI]
Abstract: In this paper we describe a discrete element method (DEM) framework we have developed for modelling the mechanical behavior of cells and tissues. By using a particle method we are able to simulate mechanical phenomena involved in tissue cell biomechanics (such as extracellular matrix degradation, secretion, growth) which would be very difficult to simulate using a continuum approach.
BibTeX: @bookchapter{2019joldesgardinerdiscrete, author = {Joldes, Grand R. and Bourantas, George C. and Wittek, Adam and Miller, Karol and Smith, David W. and Gardiner, Bruce S.}, title = {A Discrete Element Method for Modelling Cell Mechanics: Application to the Simulation of Chondrocyte Behavior in the Growth Plate}, booktitle = {Computational Biomechanics for Medicine: Measurements, Models, and Predictions}, publisher = {Springer International Publishing}, year = {2019}, pages = {93--103}, doi = {10.1007/978-3-319-75589-2_9} }
Maximum Principal AAA Wall Stress Is Proportional to Wall Thickness [Abstract]	Miller, K., Joldes, G.R., Qian, J., Patel, A.P., Jung, M.S., Tavner, A.C.R. and Wittek, A.	2019	Nielsen, P.M.F., Wittek, A., Miller, K., Doyle, B., Joldes, G.R. and Nash, M.P. (Eds), Computational Biomechanics for Medicine: Measurements, Models, and Predictions, pp. 43-53, Springer International Publishing, Cham	bookchapter	[BibTeX] [DOI]
Abstract: Abdominal aortic aneurysm (AAA) is a permanent and irreversible dilation of the lower region of the aorta. It is an asymptomatic condition which if left untreated can expand to the point of rupture. Rupture of an artery will occur when the local wall stress exceeds the local wall strength. Therefore, estimation of a patient's AAA wall stress non-invasively, quickly, and reliably is desirable. One solution to this problem is to use recently-published methods to compute AAA wall stress, using geometry from CT scans, and median arterial pressure as the load. Our method is embedded in the software platform BioPARR---Biomechanics based Prediction of Aneurysm Rupture Risk, freely available from https://bioparr.mech.uwa.edu.au/. Experience with over 50 patient-specific stress analyses, as well as common sense, suggests that the AAA wall stress is critically dependent on the local AAA wall thickness. This thickness is currently very difficult to measure in the clinical environment. Therefore, we conducted a simulation study to elucidate the relationship between the wall thickness and the maximum principal stress. The results of the analysis of three cases presented here unequivocally demonstrate that this relationship is approximately linear, bringing us closer to being able to compute predictive stress envelopes for every patient.
BibTeX: @bookchapter{2019millerwittekmaximum, author = {Miller, K. and Joldes, G. R. and Qian, J. and Patel, A. P. and Jung, M. S. and Tavner, A. C. R. and Wittek, A.}, title = {Maximum Principal AAA Wall Stress Is Proportional to Wall Thickness}, booktitle = {Computational Biomechanics for Medicine: Measurements, Models, and Predictions}, publisher = {Springer International Publishing}, year = {2019}, pages = {43--53}, doi = {10.1007/978-3-319-75589-2_5} }
Biomechanical Modelling of the Brain for Neuronavigation in Epilepsy Surgery	Miller, K., Tavner, A., Menage, L., Psanoudakis, N., Joldes, G., Warfield, S., Hyde, D. and Wittek, A.	2019	Miller, K. (Ed.), Biomechanics of the Brain, Springer	bookchapter	[BibTeX]
BibTeX: @bookchapter{2019millerwittekbiomechanical, author = {K. Miller and A.C.R. Tavner and L.P.M. Menage and N. Psanoudakis and G. Joldes and S.K. Warfield and D. Hyde and A. Wittek}, title = {Biomechanical Modelling of the Brain for Neuronavigation in Epilepsy Surgery}, booktitle = {Biomechanics of the Brain}, publisher = {Springer}, year = {2019}, edition = {2nd} }
Biomechanical Modelling of the Brain for Neurosurgical Simulation and Neuroimage Registration	Miller, K., Wittek, A., Tavner, A. and Joldes, G.	2019	Miller, K. (Ed.), Biomechanics of the Brain, Springer	bookchapter	[BibTeX]
BibTeX: @bookchapter{2019millerjoldesbiomechanical, author = {K. Miller and A. Wittek and A.C.R. Tavner and G. Joldes}, title = {Biomechanical Modelling of the Brain for Neurosurgical Simulation and Neuroimage Registration}, booktitle = {Biomechanics of the Brain}, publisher = {Springer}, year = {2019}, edition = {2nd} }
Meshless method for simulation of needle insertion into soft tissues: Preliminary results	Wittek, A., Bourantas, G., Joldes, G.R., Khau, A., Mountris, K., Singh, S. and Miller, K.	2019	Nash, M., Nielsen, P.M.F., Wittek, A. and Miller, K. (Eds), Computational Biomechanics for Medicine 2018, Springer Nature, (Accepted)	bookchapter	[BibTeX]
BibTeX: @bookchapter{2019wittekmillermeshless, author = {Wittek, A. and Bourantas, G. and Joldes, G. R. and Khau, A. and Mountris, K. and Singh, S. and Miller, K.}, title = {Meshless method for simulation of needle insertion into soft tissues: Preliminary results}, booktitle = {Computational Biomechanics for Medicine 2018}, publisher = {Springer Nature}, year = {2019}, note = {(Accepted)} }
Finite Element Algorithms for Computational Biomechanics of the Brain	Wittek, A., Joldes, G.R. and Miller, K.	2019	Miller, K. (Ed.), Biomechanics of the Brain, Springer	bookchapter	[BibTeX]
BibTeX: @bookchapter{2019wittekmillerfinite, author = {Adam Wittek and Grand Roman Joldes and Karol Miller}, title = {Finite Element Algorithms for Computational Biomechanics of the Brain}, booktitle = {Biomechanics of the Brain}, publisher = {Springer}, year = {2019}, edition = {2nd} }
Meshless Algorithms for Computational Biomechanics of the Brain	Wittek, A., Joldes, G.R. and Miller, K.	2019	Miller, K. (Ed.), Biomechanics of the Brain, Springer	bookchapter	[BibTeX]
BibTeX: @bookchapter{2019wittekmillermeshlessa, author = {Adam Wittek and Grand Roman Joldes and Karol Miller}, title = {Meshless Algorithms for Computational Biomechanics of the Brain}, booktitle = {Biomechanics of the Brain}, publisher = {Springer}, year = {2019}, edition = {2nd} }
Biomechanics of the Brain	Miller, K. (Ed.)	2019	Springer	book	[BibTeX] [DOI]
BibTeX: @book{2019millerbiomechanics,, title = {Biomechanics of the Brain}, publisher = {Springer}, year = {2019}, edition = {2nd}, doi = {10.1007/978-3-030-04996-6} }
Computational Biomechanics for Medicine 2018	Nash, M., Nielsen, P.M.F., Wittek, A. and Miller, K. (Eds)	2019	Springer Nature, (Accepted)	book	[BibTeX]
BibTeX: @book{2019nashmillercomputational,, title = {Computational Biomechanics for Medicine 2018}, publisher = {Springer Nature}, year = {2019}, note = {(Accepted)} }
Computational Biomechanics for Medicine: Measurements, Models, and Predictions [Abstract]	Nielsen, P.M., Wittek, A., Miller, K., Doyle, B., Joldes, G.R. and Nash, M.P. (Eds)	2019	Springer International Publishing, Cham	book	[BibTeX] [DOI]
Abstract: This volume comprises the latest developments in both fundamental science and patient-specific applications, discussing topics such as: cellular mechanics, injury biomechanics, biomechanics of the heart and vascular system, algorithms of computational biomechanics for medical image analysis, and both patient-specific fluid dynamics and solid mechanics simulations. With contributions from researchers world-wide, Computational Biomechanics for Medicine: Measurments, Models, and Predictions provides an opportunity for specialists in the field to present their latest methodologies and advancements.
BibTeX: @book{2019nielsennashcomputational,, title = {Computational Biomechanics for Medicine: Measurements, Models, and Predictions}, publisher = {Springer International Publishing}, year = {2019}, doi = {10.1007/978-3-319-75589-2} }
Strong- and Weak-Form Meshless Methods in Computational Biomechanics [Abstract]	Bourantas, G., Joldes, G., Wittek, A. and Miller, K.	2018	Cerrolaza, M., Shefelbine, S.J. and Garzón-Alvarado, D. (Eds), Numerical Methods and Advanced Simulation in Biomechanics and Biological Processes, pp. 325-339, Academic Press	bookchapter	[BibTeX] [DOI]
Abstract: Meshless methods (MMs) were introduced in the late 1970s to solve problems in astrophysics. In MMs the spatial domain is represented by a set of nodes (cloud of points) and not discretized by elements as in most of the mesh-based methods (finite difference method, finite element method, finite volume method); consequently, there is no need for predefined connectivity between the nodes. In this chapter we are going to give an overview of applications, advantages, and disadvantages of various MMs developed and applied in the context of computational biomechanics. Strong and weak formulations will be presented, focusing on the novel interpolation schemes such as modified moving least squares and discretization correction particle strength exchange method, along with the meshless total Lagrangian explicit dynamics method. The applicability of the methods in multiscale problems and their inherent parallelization will be depicted through various applications, along with their advantages over the traditional mesh-based numerical methods. MMs can be considered as mainstream numerical methods able to tackle demanding engineering applications. Intensive and rigorous research in the field will make MMs robust enough to be used by industry.
BibTeX: @bookchapter{2018bourantasmillerstrong, author = {G.C. Bourantas and G.R. Joldes and A. Wittek and K. Miller}, title = {Strong- and Weak-Form Meshless Methods in Computational Biomechanics}, booktitle = {Numerical Methods and Advanced Simulation in Biomechanics and Biological Processes}, publisher = {Academic Press}, year = {2018}, pages = {325--339}, doi = {10.1016/B978-0-12-811718-7.00018-6} }
Strong-form approach to elasticity: hybrid Finite Difference – Meshless Collocation Method (FDMCM) [Abstract]	Bourantas, G., Mountris, K., Loukopoulos, V., Lavier, L., Joldes, G., Wittek, A. and Miller, K.	2018	Applied Mathematical Modelling, vol. 57, pp. 316-338	article	[BibTeX] [PDF] [DOI]
Abstract: We propose a numerical method that combines the Finite Difference (FD) and strong form (collocation) Meshless Method (MM) for solving linear elasticity equations. We call this new method FDMCM. The FDMCM scheme uses a uniform Cartesian grid embedded in complex geometries and applies both methods to calculate spatial derivatives. The spatial domain is represented by a set of nodes categorized as i) boundary and near boundary nodes, and ii) interior nodes. For boundary and near boundary nodes, where the finite difference stencil cannot be defined, the Discretization Corrected Particle Strength Exchange (DC PSE) scheme is used for derivative evaluation, while for interior nodes standard second order Finite Differences are used. FDMCM method combines the advantages of both FD and DC PSE methods. It supports a fast and simple generation of grids and provides convergence rates comparable to weak formulations. We demonstrate the appropriateness and robustness of the proposed scheme through various benchmark problems in 2D and 3D. Numerical results show good accuracy and h- convergence properties. The ease of computational grid generation makes the method particularly suited for problems where geometries are very complicated and known only imperfectly from images, frequently occurring in e.g. geomechanics and patient-specific biomechanics, where the proposed FDMCM method, after its extension to non-linear regime, appears to be a promising alternative to the traditional weak form-based numerical schemes used in the field.
BibTeX: @article{2018bourantasmillerAMMstrong, author = {G.C. Bourantas and K.A. Mountris and V.C. Loukopoulos and L. Lavier and G.R. Joldes and A. Wittek and K. Miller}, title = {Strong-form approach to elasticity: hybrid Finite Difference – Meshless Collocation Method (FDMCM)}, journal = {Applied Mathematical Modelling}, year = {2018}, volume = {57}, pages = {316--338}, doi = {10.1016/j.apm.2017.09.028} }
Computational monitoring in real time: review of methods and applications [Abstract]	Dyskin, A.V., Basarir, H., Doherty, J., Elchalakani, M., Joldes, G.R., Karrech, A., Lehane, B., Miller, K., Pasternak, E., Shufrin, I. and Wittek, A.	2018	Geomechanics and Geophysics for Geo-Energy and Geo-Resources, vol. 4(3), pp. 235-271	article	[BibTeX] [PDF] [DOI]
Abstract: Continuous monitoring of mechanical parameters determining the state of natural and man-made systems is essential in a wide range of engineering disciplines from mechanical to civil and geotechnical engineering. To be effective, the monitoring response time needs to be commensurate with the characteristic time of variation of the processes being monitored e.g. from seconds as for example in some machinery, to weeks and months for mining excavations and years in the case of structures. The methods of measurement can therefore differ significantly for different applications. In spite of this, the methods of information processing---the computational monitoring---have considerable commonality. This review focuses on the methods of computational monitoring in solid and structural mechanics problems in different engineering applications. The traditional methods of monitoring are reviewed along with the corresponding computational and measurement methods. The basic principles of the computational monitoring in real time are established.
BibTeX: @article{2018sepdyskinwittekGaGfGaGcomputational, author = {Dyskin, Arcady V. and Basarir, Hakan and Doherty, James and Elchalakani, Mohamed and Joldes, Grand R. and Karrech, Ali and Lehane, Barry and Miller, Karol and Pasternak, Elena and Shufrin, Igor and Wittek, Adam}, title = {Computational monitoring in real time: review of methods and applications}, journal = {Geomechanics and Geophysics for Geo-Energy and Geo-Resources}, year = {2018}, volume = {4}, number = {3}, pages = {235--271}, doi = {10.1007/s40948-018-0086-6} }
A simple method of incorporating the effect of the Uniform Stress Hypothesis in arterial wall stress computations	Joldes, G., Noble, C., Polzer, S., Taylor, Z., Wittek, A. and Miller, K.	2018	Acta of Bioengineering and Biomechanics, vol. 20(3), pp. 59-67	article	[BibTeX] [PDF] [DOI] [URL]
BibTeX: @article{2018joldesmillerAoBaBsimple, author = {G.R. Joldes and C. Noble and S. Polzer and Z.A. Taylor and A. Wittek and K. Miller}, title = {A simple method of incorporating the effect of the Uniform Stress Hypothesis in arterial wall stress computations}, journal = {Acta of Bioengineering and Biomechanics}, year = {2018}, volume = {20}, number = {3}, pages = {59--67}, url = {https://www.actabio.pwr.wroc.pl/Vol20No3/48.pdf}, doi = {10.5277/ABB-01143-2018-03} }
Prediction of brain deformations and risk of traumatic brain injury due to closed-head impact: quantitative analysis of the effects of boundary conditions and brain tissue constitutive model [Abstract]	Wang, F., Han, Y., Wang, B., Peng, Q., Huang, X., Miller, K. and Wittek, A.	2018	Biomechanics and Modeling in Mechanobiology, vol. 17(4), pp. 1165-1185	article	[BibTeX] [PDF] [DOI]
Abstract: In this study, we investigate the effects of modelling choices for the brain--skull interface (layers of tissues between the brain and skull that determine boundary conditions for the brain) and the constitutive model of brain parenchyma on the brain responses under violent impact as predicted using computational biomechanics model. We used the head/brain model from Total HUman Model for Safety (THUMS)---extensively validated finite element model of the human body that has been applied in numerous injury biomechanics studies. The computations were conducted using a well-established nonlinear explicit dynamics finite element code LS-DYNA. We employed four approaches for modelling the brain--skull interface and four constitutive models for the brain tissue in the numerical simulations of the experiments on post-mortem human subjects exposed to violent impacts reported in the literature. The brain--skull interface models included direct representation of the brain meninges and cerebrospinal fluid, outer brain surface rigidly attached to the skull, frictionless sliding contact between the brain and skull, and a layer of spring-type cohesive elements between the brain and skull. We considered Ogden hyperviscoelastic, Mooney--Rivlin hyperviscoelastic, neo--Hookean hyperviscoelastic and linear viscoelastic constitutive models of the brain tissue. Our study indicates that the predicted deformations within the brain and related brain injury criteria are strongly affected by both the approach of modelling the brain--skull interface and the constitutive model of the brain parenchyma tissues. The results suggest that accurate prediction of deformations within the brain and risk of brain injury due to violent impact using computational biomechanics models may require representation of the meninges and subarachnoidal space with cerebrospinal fluid in the model and application of hyperviscoelastic (preferably Ogden-type) constitutive model for the brain tissue.
BibTeX: @article{2018augwangwittekBaMiMprediction, author = {Wang, Fang and Han, Yong and Wang, Bingyu and Peng, Qian and Huang, Xiaoqun and Miller, Karol and Wittek, Adam}, title = {Prediction of brain deformations and risk of traumatic brain injury due to closed-head impact: quantitative analysis of the effects of boundary conditions and brain tissue constitutive model}, journal = {Biomechanics and Modeling in Mechanobiology}, year = {2018}, volume = {17}, number = {4}, pages = {1165--1185}, doi = {10.1007/s10237-018-1021-z} }
An implicit potential method along with a meshless technique for incompressible fluid flows for regular and irregular geometries in 2D and 3D [Abstract]	Bourantas, G., Loukopoulos, V., Chowdhury, H., Joldes, G., Miller, K. and Bordas, S.	2017	Engineering Analysis with Boundary Elements, vol. 77, pp. 97-111	article	[BibTeX] [PDF] [DOI]
Abstract: We present the Implicit Potential (IPOT) numerical scheme developed in the framework of meshless point collocation. The proposed scheme is used for the numerical solution of the steady state, incompressible Navier-Stokes (N-S) equations in their primitive variable (u-v-w-p) formulation. The governing equations are solved in their strong form using either a collocated or a semi-staggered type meshless nodal configuration. The unknown field functions and derivatives are calculated using the Modified Moving Least Squares (MMLS) interpolation method. Both velocity-correction and pressure-correction methods applied ensure the incompressibility constraint and mass conservation. The proposed meshless point collocation (MPC) scheme has the following characteristics: (i) it can be applied, in a straightforward manner to: steady, unsteady, internal and external fluid flows in 2D and 3D, (ii) it equally applies to regular an irregular geometries, (iii) a distribution of points is sufficient, no numerical integration in space nor any mesh structure are required, (iv) there is no need for pressure boundary conditions since no pressure constitutive equation is solved, (v) it is quite simple and accurate, (vi) results can be obtained using collocated or semi-staggered nodal distributions, (vii) there is no need to compute the velocity potential nor the unit normal vectors and (viii) there is no need for a curvilinear system of coordinates. Simulations of fluid flow in 2D and 3D for regular and irregular geometries indicate the validity of the proposed methodology.
BibTeX: @article{2017bourantasbordasEAwBEimplicit, author = {G.C. Bourantas and V.C. Loukopoulos and H.A. Chowdhury and G.R. Joldes and K. Miller and S.P.A. Bordas}, title = {An implicit potential method along with a meshless technique for incompressible fluid flows for regular and irregular geometries in 2D and 3D}, journal = {Engineering Analysis with Boundary Elements}, year = {2017}, volume = {77}, pages = {97--111}, doi = {10.1016/j.enganabound.2017.01.009} }
An Element Free Galerkin Method Based on the Modified Moving Least Squares Approximation [Abstract]	Chowdhury, H.A., Wittek, A., Miller, K. and Joldes, G.R.	2017	Journal of Scientific Computing, vol. 71(3), pp. 1197-1211	article	[BibTeX] [PDF] [DOI]
Abstract: This paper demonstrates that the recently developed modified moving least squares (MMLS) approximation possess the necessary properties which allow its use as an element free Galerkin (EFG) approximation method. Specifically, the consistency and invariance properties for the MMLS are proven. We demonstrate that MMLS shape functions form a partition of unity and the MMLS approximation satisfies the patch test. The invariance properties are important for the accurate computation of the shape functions by using translation and scaling to a canonical domain. We compare the performance of the EFG method based on MMLS, which uses quadratic base functions, to the performance of the EFG method which uses classical MLS with linear base functions, using both 2D and 3D examples. In 2D we solve an elasticity problem which has an analytical solution (bending of a Timoshenko beam) while in 3D we solve an elasticity problem which has an exact finite element solution (unconstrained compression of a cube). We also solve a complex problem involving complicated geometry, non-linear material, large deformations and contacts. The simulation results demonstrate the superior performance of the MMLS over classical MLS in terms of solution accuracy, while shape functions can be computed using the same nodal distribution and support domain size for both methods.
BibTeX: @article{2017junchowdhuryjoldesJoSCelement, author = {Chowdhury, Habibullah Amin and Wittek, Adam and Miller, Karol and Joldes, Grand Roman}, title = {An Element Free Galerkin Method Based on the Modified Moving Least Squares Approximation}, journal = {Journal of Scientific Computing}, year = {2017}, volume = {71}, number = {3}, pages = {1197--1211}, doi = {10.1007/s10915-016-0337-z} }
A new method for essential boundary conditions imposition in explicit meshless methods [Abstract]	Joldes, G.R., Chowdhury, H., Wittek, A. and Miller, K.	2017	Engineering Analysis with Boundary Elements, vol. 80, pp. 94-104	article	[BibTeX] [PDF] [DOI]
Abstract: In this paper we present a new technique of enforcing Essential Boundary Conditions (EBC) in Meshless Methods (MMs) based on the Element Free Galerkin (EFG) principles. Imposing EBC is a fundamental issue in MMs. The imposition of prescribed displacement values on the boundary in MMs based on approximating shape functions is not as straightforward as in the Finite Element Method (FEM) because the meshless shape functions are generally not interpolating at nodes. Furthermore, many techniques of enforcing EBC are not compatible with explicit time integration schemes. This paper describes a new method of imposing EBC in EFG based MMs suitable for explicit time integration, named Essential Boundary Conditions Imposition in Explicit Meshless (EBCIEM). The effectiveness of the proposed method is demonstrated using both 2D and 3D numerical examples.
BibTeX: @article{2017joldesmillerEAwBEnew, author = {Grand Roman Joldes and Habib Chowdhury and Adam Wittek and Karol Miller}, title = {A new method for essential boundary conditions imposition in explicit meshless methods}, journal = {Engineering Analysis with Boundary Elements}, year = {2017}, volume = {80}, pages = {94--104}, doi = {10.1016/j.enganabound.2017.03.011} }
BioPARR: A software system for estimating the rupture potential index for abdominal aortic aneurysms [Abstract]	Joldes, G.R., Miller, K., Wittek, A., Forsythe, R.O., Newby, D.E. and Doyle, B.J.	2017	Scientific Reports, vol. 7, pp. 4641	article	[BibTeX] [PDF] [DOI]
Abstract: An abdominal aortic aneurysm (AAA) is a permanent and irreversible dilation of the lower region of the aorta. It is a symptomless condition that, if left untreated, can expand until rupture. Despite ongoing efforts, an efficient tool for accurate estimation of AAA rupture risk is still not available. Furthermore, a lack of standardisation across current approaches and specific obstacles within computational workflows limit the translation of existing methods to the clinic. This paper presents BioPARR (Biomechanics based Prediction of Aneurysm Rupture Risk), a software system to facilitate the analysis of AAA using a finite element analysis based approach. Except semi-automatic segmentation of the AAA and intraluminal thrombus (ILT) from medical images, the entire analysis is performed automatically. The system is modular and easily expandable, allows the extraction of information from images of different modalities (e.g. CT and MRI) and the simulation of different modelling scenarios (e.g. with/without thrombus). The software uses contemporary methods that eliminate the need for patient-specific material properties, overcoming perhaps the key limitation to all previous patient-specific analysis methods. The software system is robust, free, and will allow researchers to perform comparative evaluation of AAA using a standardised approach. We report preliminary data from 48 cases.
BibTeX: @article{2017joldesdoyleSRbioparr, author = {Grand Roman Joldes and Karol Miller and Adam Wittek and Rachael O. Forsythe and David E. Newby and Barry J. Doyle}, title = {BioPARR: A software system for estimating the rupture potential index for abdominal aortic aneurysms}, journal = {Scientific Reports}, year = {2017}, volume = {7}, pages = {4641}, doi = {10.1038/s41598-017-04699-1} }
Computation of accurate solutions when using element-free Galerkin methods for solving structural problems [Abstract]	Joldes, G.R., Teakle, P., Wittek, A. and Miller, K.	2017	Engineering Computations, vol. 34(3), pp. 902-920	article	[BibTeX] [DOI]
Abstract: Purpose This paper investigates the application of adaptive integration in element-free Galerkin methods for solving problems in structural and solid mechanics in order to obtain accurate reference solutions. Design/methodology/approach An adaptive quadrature algorithm which allows user control over integration accuracy, previously developed for integrating boundary value problems, is adapted to elasticity problems. The algorithm allows the development of a convergence study procedure that takes into account both integration and discretisation errors. The convergence procedure is demonstrated using an elasticity problem which has an analytical solution and is then applied to accurately solve a soft tissue extension problem involving large deformations. Findings The developed convergence procedure, based on the presented adaptive integration scheme, allows the computation of accurate reference solutions for challenging problems which do not have an analytical or finite element solution. Practical implications The convergence procedure proposed in this paper allows the user to independently examine and control the contribution of integration and discretisation errors to the overall solution error. The presented procedure allows the computation of reference solutions for very challenging problems which do not have an analytical or even a finite element solution (such as very large deformation problems). Originality/value This paper investigates the application of adaptive quadrature to solid mechanics problems in engineering analysis using the element-free Galerkin method in order to obtain accurate reference solutions. The proposed convergence procedure allows the user to independently examine and control the contribution of integration and discretisation errors to the overall solution error. This allows the computation of reference solutions for very challenging problems which do not have an analytical or even a finite element solution (such as very large deformation problems).
BibTeX: @article{2017marjoldesmillerECcomputation, author = {Grand Roman Joldes and Peter Teakle and Adam Wittek and Karol Miller}, title = {Computation of accurate solutions when using element-free Galerkin methods for solving structural problems}, journal = {Engineering Computations}, year = {2017}, volume = {34}, number = {3}, pages = {902--920}, doi = {10.1108/ec-01-2016-0017} }
A comparison of hemodynamic metrics and intraluminal thrombus burden in a common iliac artery aneurysm [Abstract]	Kelsey, L.J., Powell, J.T., Norman, P.E., Miller, K. and Doyle, B.J.	2017	International Journal for Numerical Methods in Biomedical Engineering, vol. 33(5), pp. e2821	article	[BibTeX] [PDF] [DOI]
Abstract: Aneurysms of the common iliac artery (CIAA) are typically found in association with an abdominal aortic aneurysm (AAA). Isolated CIAAs, in the absence of an AAA, are uncommon. Similar to AAAs, CIAA may develop intraluminal thrombus (ILT). As isolated CIAAs have a contralateral common iliac artery for comparison, they provide an opportunity to study the hemodynamic mechanisms behind ILT formation.In this study, we compared a large isolated CIAA and the contralateral iliac artery using computational fluid dynamics to determine if hemodynamic metrics correlate with the location of ILT. We performed a comprehensive computational fluid dynamics study and investigated the residence time of platelets and monocytes, velocity fields, time-averaged wall shear stress, oscillatory shear index, and endothelial cell activation potential. We then correlated these data to ILT burden determined with computed tomography.We found that high cell residence times, low time-averaged wall shear stress, high oscillatory shear index, and high endothelial cell activation potential all correlate with regions of ILT development. Our results show agreement with previous hypotheses of thrombus formation in AAA and provide insights into the computational hemodynamics of iliac artery aneurysms.
BibTeX: @article{2017sepkelseydoyleIJfNMiBEcomparison, author = {Kelsey, Lachlan J. and Powell, Janet T. and Norman, Paul E. and Miller, Karol and Doyle, Barry J.}, title = {A comparison of hemodynamic metrics and intraluminal thrombus burden in a common iliac artery aneurysm}, journal = {International Journal for Numerical Methods in Biomedical Engineering}, year = {2017}, volume = {33}, number = {5}, pages = {e2821}, doi = {10.1002/cnm.2821} }
The Effects of Geometric Variation from OCT-Derived 3D Reconstructions on Wall Shear Stress in a Patient-Specific Coronary Artery [Abstract]	Kelsey, L.J., Schultz, C., Miller, K. and Doyle, B.J.	2017	Wittek, A., Joldes, G., Nielsen, P.M., Doyle, B.J. and Miller, K. (Eds), Computational Biomechanics for Medicine: From Algorithms to Models and Applications, pp. 1-13, Springer International Publishing	incollection	[BibTeX] [DOI]
Abstract: Computational fluid dynamics (CFD) can be used to model the blood flow in patient-specific arterial geometries and predict atherosclerotic plaque progression, as the site specificity of plaques has been shown to depend on the wall shear stress (WSS) experienced by an artery’s endothelial layer. The level of artery wall detail in CFD models is expected to underpin predictions of plaque deposition, as it influences the computation of WSS. In this study, the sensitivity of WSS computation to geometric variation in a (proximally) stented left anterior descending (LAD) coronary artery geometry is investigated. The geometry is reconstructed from intravascular optical coherence tomography (OCT) images, which are registered and merged with computed tomography (CT) to include surrounding arteries. The WSS is modelled for low-, medium- and high-resolution geometries; created by altering the point resolution of the contour algorithm used to trace the (OCT imaged) artery lumen. The results show that areas of low WSS (and thus high thrombotic susceptibility) in the stented portion of the artery depended greatly on the resolution of the geometric reconstruction. Compared with the high-resolution geometry, the low- and medium-resolutions failed to accurately determine the areas of low WSS in the stented region, as minor geometric features were inadequately represented. The sensitivity of WSS to geometric variation is also relevant to analyses using coronary artery geometries derived from other imaging modalities (particularly those of lower resolution than OCT).
BibTeX: @incollection{2017kelseydoyleeffects, author = {Lachlan J. Kelsey and Carl Schultz and Karol Miller and Barry J. Doyle}, title = {The Effects of Geometric Variation from OCT-Derived 3D Reconstructions on Wall Shear Stress in a Patient-Specific Coronary Artery}, booktitle = {Computational Biomechanics for Medicine: From Algorithms to Models and Applications}, publisher = {Springer International Publishing}, year = {2017}, pages = {1--13}, doi = {10.1007/978-3-319-54481-6_1} }
Constitutive Modelling of Lamb Aorta [Abstract]	Macrae, R.A., Pillow, J., Miller, K. and Doyle, B.J.	2017	Wittek, A., Joldes, G., Nielsen, P.M., Doyle, B.J. and Miller, K. (Eds), Computational Biomechanics for Medicine: From Algorithms to Models and Applications, pp. 15-25, Springer, Cham	incollection	[BibTeX] [DOI]
Abstract: Vascular inflammation is an established marker of cardiovascular pathogenesis, particularly atherosclerosis, but its role on arterial tissue biomechanics is not well understood. Its impact on the biomechanics of the aorta can yield valuable data for elucidating its role in disease formation, as well as leading to the development of valuable predictive models for surgery and new treatments. Changes in arterial biomechanics can lead to arterial remodelling and dysfunction, and so its quantification can provide insight into the nature of inflammatory processes. To gain further insight into these processes we investigated the biomechanical behaviour of lamb aortas from inflamed and control groups through the development of a constitutive model. The development of reliable constitutive models of the artery is necessary in order to fully understand the mechanical component of cardiovascular disease pathogenesis and vascular remodelling. We used a foetal sheep model of systemic inflammation induced by prenatal lipopolysaccharide (LPS) treatment (n = 6) to investigate the effects of short-term inflammation on the passive biomechanical response of the aorta. We subjected samples cut from aortas (LPS, n = 6; control, n = 4) to uniaxial tension testing until failure, measuring vessel dimensions and force–displacement curves. Upon calibration of a first order Ogden model to fit the data, a difference was found in the μ parameter (4.43 × 10−4 ± 3.67 × 10−4 control, 7.77 × 10−4 ± 6.96 × 10−4 LPS-treated) and no difference was noted in the α parameter (12.96 ± 2.145 control, 12.65 ± 3.378 LPS-treated), although neither finding was statistically significant (p > 0.4, p > 0.8, respectively). Our preliminary ex-vivo data suggests that intra-amniotic LPS-induced systemic inflammation does not significantly change the stiffness or strength of the aorta. With further work, we hope our study can help fully elucidate the role of inflammation on aorta biomechanics.
BibTeX: @incollection{2017macraedoyleconstitutive, author = {Ryley A. Macrae and Jane Pillow and Karol Miller and Barry J. Doyle}, title = {Constitutive Modelling of Lamb Aorta}, booktitle = {Computational Biomechanics for Medicine: From Algorithms to Models and Applications}, publisher = {Springer}, year = {2017}, pages = {15--25}, doi = {10.1007/978-3-319-54481-6_2} }
Computation of Brain Deformations Due to Violent Impact: Quantitative Analysis of the Importance of the Choice of Boundary Conditions and Brain Tissue Constitutive Model [Abstract]	Wang, F., Geng, Z., Agrawal, S., Han, Y., Miller, K. and Wittek, A.	2017	Wittek, A., Joldes, G., Nielsen, P.M., Doyle, B.J. and Miller, K. (Eds), Computational Biomechanics for Medicine: From Algorithms to Models and Applications, pp. 159-173, Springer, Cham	incollection	[BibTeX] [DOI]
Abstract: The objective of this study is to quantify the effects of approach for modelling the brain-skull interface and constitutive model of the brain parenchyma on predicting the brain deformations using a previously validated finite element head-brain model (Total HUman Model for Safety, THUMS, was used). Four approaches for modelling of the brain-skull interface and two constitutive models (linear viscoelastic and Odgen hyperviscoelastic) of the brain tissue were employed in computer simulations of the experiments reported in the literature. Comparison of the predicted and experimentally determined magnitude and shape of trajectories of selected points within the brain as well as the maximum principal and shear strain within the brain was conducted. The comparison indicates that the predicted brain responses were strongly affected by both analysed factors. The results suggest that accurate prediction of brain deformations due to violent impact requires a model of the brain-skull interface that allows for movement between the brain outer surface and skull, while preventing complete separation between the brain and skull, and constitutive model that accounts for non-linear stress-strain relationship of the brain tissues.
BibTeX: @incollection{2017wangwittekcomputation, author = {Fang Wang and Zhengyang Geng and Sudip Agrawal and Yong Han and Karol Miller and Adam Wittek}, title = {Computation of Brain Deformations Due to Violent Impact: Quantitative Analysis of the Importance of the Choice of Boundary Conditions and Brain Tissue Constitutive Model}, booktitle = {Computational Biomechanics for Medicine: From Algorithms to Models and Applications}, publisher = {Springer}, year = {2017}, pages = {159--173}, doi = {10.1007/978-3-319-54481-6_14} }
Computational Biomechanics for Medicine: From Algorithms to Models and Applications	Wittek, A., Joldes, G., Nielsen, P.M., Doyle, B.J. and Miller, K. (Eds)	2017	Springer, Cham	book	[BibTeX] [DOI]
BibTeX: @book{2017wittekmillercomputational,, title = {Computational Biomechanics for Medicine: From Algorithms to Models and Applications}, publisher = {Springer}, year = {2017}, doi = {10.1007/978-3-319-54481-6} }
Commentary: Computational Biomechanics-Based Rupture Prediction of Abdominal Aortic Aneurysms.	Doyle, B.J., Miller, K., Newby, D.E. and Hoskins, P.R.	2016	Journal of Endovascular Therapy, vol. 23(1), pp. 121-124	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2016febdoylehoskinsJETcommentary, author = {Doyle, Barry J and Miller, Karol and Newby, David E and Hoskins, Peter R}, title = {Commentary: Computational Biomechanics-Based Rupture Prediction of Abdominal Aortic Aneurysms.}, journal = {Journal of Endovascular Therapy}, school = {British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Scotland, UK.}, year = {2016}, volume = {23}, number = {1}, pages = {121--124}, doi = {10.1177/1526602815615821} }
Computational Biomechanics for Medicine: Imaging, Modeling and Computing	Joldes, G.R., Doyle, B., Wittek, A., Nielsen, P.M. and Miller, K.	2016	Springer	book	[BibTeX]
BibTeX: @book{2016joldesmillercomputational, author = {Joldes, Grand R and Doyle, Barry and Wittek, Adam and Nielsen, Poul MF and Miller, Karol}, title = {Computational Biomechanics for Medicine: Imaging, Modeling and Computing}, publisher = {Springer}, year = {2016} }
Traumatic Brain Injury: An Investigation into Shear Waves Interference Effects	Joldes, G.R., Lanzara, A.L., Wittek, A., Doyle, B. and Miller, K.	2016	Computational Biomechanics for Medicine, pp. 177-186, Springer International Publishing	bookchapter	[BibTeX]
BibTeX: @bookchapter{2016joldesmillertraumatic, author = {Joldes, Grand R. and Lanzara, Alesio L. and Wittek, Adam and Doyle, Barry and Miller, Karol}, title = {Traumatic Brain Injury: An Investigation into Shear Waves Interference Effects}, booktitle = {Computational Biomechanics for Medicine}, publisher = {Springer International Publishing}, year = {2016}, pages = {177--186} }
A simple, effective and clinically applicable method to compute abdominal aortic aneurysm wall stress. [Abstract]	Joldes, G.R., Miller, K., Wittek, A. and Doyle, B.	2016	Journal of the Mechanical Behavior of Biomedical Materials, vol. 58, pp. 139-148	article	[BibTeX] [PDF] [DOI]
Abstract: Abdominal aortic aneurysm (AAA) is a permanent and irreversible dilation of the lower region of the aorta. It is a symptomless condition that if left untreated can expand to the point of rupture. Mechanically-speaking, rupture of an artery occurs when the local wall stress exceeds the local wall strength. It is therefore desirable to be able to non-invasively estimate the AAA wall stress for a given patient, quickly and reliably. In this paper we present an entirely new approach to computing the wall tension (i.e. the stress resultant equal to the integral of the stresses tangent to the wall over the wall thickness) within an AAA that relies on trivial linear elastic finite element computations, which can be performed instantaneously in the clinical environment on the simplest computing hardware. As an input to our calculations we only use information readily available in the clinic: the shape of the aneurysm in-vivo, as seen on a computed tomography (CT) scan, and blood pressure. We demonstrate that tension fields computed with the proposed approach agree well with those obtained using very sophisticated, state-of-the-art non-linear inverse procedures. Using magnetic resonance (MR) images of the same patient, we can approximately measure the local wall thickness and calculate the local wall stress. What is truly exciting about this simple approach is that one does not need any information on material parameters; this supports the development and use of patient-specific modelling (PSM), where uncertainty in material data is recognised as a key limitation. The methods demonstrated in this paper are applicable to other areas of biomechanics where the loads and loaded geometry of the system are known.
BibTeX: @article{2016mayjoldesdoyleJMBBMsimple, author = {Joldes, Grand Roman and Miller, Karol and Wittek, Adam and Doyle, Barry}, title = {A simple, effective and clinically applicable method to compute abdominal aortic aneurysm wall stress.}, journal = {Journal of the Mechanical Behavior of Biomedical Materials}, school = {Vascular Engineering, Intelligent Systems for Medicine Laboratory, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia; Centre for Cardiovascular Science, The University of Edinburgh, UK.}, year = {2016}, volume = {58}, pages = {139--148}, doi = {10.1016/j.jmbbm.2015.07.029} }
The Influence of Downstream Branching Arteries on Upstream Haemodynamics	Kelsey, L.J., Miller, K., Norman, P.E., Powell, J.T. and Doyle, B.J.	2016	Journal of Biomechanics, Elsevier	article	[BibTeX] [DOI]
BibTeX: @article{2016kelseydoyleJoBinfluence, author = {Kelsey, Lachlan J and Miller, Karol and Norman, Paul E and Powell, Janet T and Doyle, Barry J}, title = {The Influence of Downstream Branching Arteries on Upstream Haemodynamics}, journal = {Journal of Biomechanics}, publisher = {Elsevier}, year = {2016}, doi = {10.1016/j.jbiomech.2016.07.023} }
Biomechanical model for computing deformations for whole-body image registration: A meshless approach. [Abstract]	Li, M., Miller, K., Joldes, G.R., Kikinis, R. and Wittek, A.	2016	International Journal for Numerical Methods in Biomedical Engineering	article	[BibTeX] [PDF] [DOI]
Abstract: Patient-specific biomechanical models have been advocated as a tool for predicting deformations of soft body organs/tissue for medical image registration (aligning two sets of images) when differences between the images are large. However, complex and irregular geometry of the body organs makes generation of patient-specific biomechanical models very time consuming. Meshless discretisation has been proposed to solve this challenge. However, applications so far have been limited to 2-D models and computing single organ deformations. In this study, 3-D comprehensive patient-specific non-linear biomechanical models implemented using Meshless Total Lagrangian Explicit Dynamics (MTLED) algorithms are applied to predict a 3-D deformation field for whole-body image registration. Unlike a conventional approach which requires dividing (segmenting) the image into non-overlapping constituents representing different organs/tissues, the mechanical properties are assigned using the Fuzzy C-Means (FCM) algorithm without the image segmentation. Verification indicates that the deformations predicted using the proposed meshless approach are for practical purposes the same as those obtained using the previously validated finite element models. To quantitatively evaluate the accuracy of the predicted deformations, we determined the spatial misalignment between the registered (i.e. source images warped using the predicted deformations) and target images by computing the edge-based Hausdorff distance. The Hausdorff distance-based evaluation determines that our meshless models led to successful registration of the vast majority of the image features.
BibTeX: @article{2016janliwittekIJNMBEbiomechanical, author = {Li, Mao and Miller, Karol and Joldes, Grand Roman and Kikinis, Ron and Wittek, Adam}, title = {Biomechanical model for computing deformations for whole-body image registration: A meshless approach.}, journal = {International Journal for Numerical Methods in Biomedical Engineering}, school = {Intelligent Systems for Medicine Laboratory, School of Mechanical and Chemical Engineering, The University of Western Australia, Perth, Australia.}, year = {2016}, doi = {10.1002/cnm.2771} }
Fuzzy Tissue Classification for Non-Linear Patient-Specific Biomechanical Models for Whole-Body Image Registration	Li, M., Wittek, A., Joldes, G.R. and Miller, K.	2016	Computational Biomechanics for Medicine, pp. 85-96, Springer International Publishing	bookchapter	[BibTeX]
BibTeX: @bookchapter{2016limillerfuzzy, author = {Li, Mao and Wittek, Adam and Joldes, Grand R and Miller, Karol}, title = {Fuzzy Tissue Classification for Non-Linear Patient-Specific Biomechanical Models for Whole-Body Image Registration}, booktitle = {Computational Biomechanics for Medicine}, publisher = {Springer International Publishing}, year = {2016}, pages = {85--96} }
Methods in Mechanical Testing of Arterial Tissue: A Review [Abstract]	Macrae, R., Miller, K. and Doyle, B.	2016	Strain, vol. 52(5), pp. 380-399	article	[BibTeX] [PDF] [DOI]
Abstract: Mechanical testing of arterial tissue can provide unique insights into its behaviour. As measurement and computational techniques continue to advance, new applications can be discovered that increase the accuracy of characterising tissue behaviour. This review provides an overview of the general considerations involved in testing arterial tissue and discusses the more commonly employed in vitro techniques used to assess the mechanical properties of arterial tissue, as well as emerging techniques. The more common methods discussed are uniaxial, planar biaxial and inflation testing. With the increasing precision and versatility of optical measuring systems and the rising interest in the mechanical behaviour of vessels with complex geometries and material properties, we also discuss the emerging trend of full-field measurement systems. Mechanical testing can be combined with bioreactor techniques to characterise the dynamic remodelling of arterial tissue in response to its mechanical environment. The analysis and characterisation provided by advanced mechanical testing techniques can produce and inform more accurate surgical simulations, as well as aid in the risk prediction and modelling of pathological conditions.
BibTeX: @article{2016macraedoyleSmethods, author = {Macrae, R.A. and Miller, K. and Doyle, B.J.}, title = {Methods in Mechanical Testing of Arterial Tissue: A Review}, journal = {Strain}, year = {2016}, volume = {52}, number = {5}, pages = {380--399}, doi = {10.1111/str.12183} }
Influence of Geometry and Mechanical Properties on the Accuracy of Patient-Specific Simulation of Women Pelvic Floor. [Abstract]	Mayeur, O., Witz, J.-F., Lecomte, P., Brieu, M., Cosson, M. and Miller, K.	2016	Annals of Biomedical Engineering, vol. 44(1), pp. 202-212	article	[BibTeX] [PDF] [DOI]
Abstract: The woman pelvic system involves multiple organs, muscles, ligaments, and fasciae where different pathologies may occur. Here we are most interested in abnormal mobility, often caused by complex and not fully understood mechanisms. Computer simulation and modeling using the finite element (FE) method are the tools helping to better understand the pathological mobility, but of course patient-specific models are required to make contribution to patient care. These models require a good representation of the pelvic system geometry, information on the material properties, boundary conditions and loading. In this contribution we focus on the relative influence of the inaccuracies in geometry description and of uncertainty of patient-specific material properties of soft connective tissues. We conducted a comparative study using several constitutive behavior laws and variations in geometry description resulting from the imprecision of clinical imaging and image analysis. We find that geometry seems to have the dominant effect on the pelvic organ mobility simulation results. Provided that proper finite deformation non-linear FE solution procedures are used, the influence of the functional form of the constitutive law might be for practical purposes negligible. These last findings confirm similar results from the fields of modeling neurosurgery and abdominal aortic aneurysms.
BibTeX: @article{2016janmayeurmillerABEinfluence, author = {Mayeur, Olivier and Witz, Jean-François and Lecomte, Pauline and Brieu, Mathias and Cosson, Michel and Miller, Karol}, title = {Influence of Geometry and Mechanical Properties on the Accuracy of Patient-Specific Simulation of Women Pelvic Floor.}, journal = {Annals of Biomedical Engineering}, school = {Intelligent Systems for Medicine Laboratory, The University of Western Australia, Crawley, Perth, WA, 6009, Australia.}, year = {2016}, volume = {44}, number = {1}, pages = {202--212}, doi = {10.1007/s10439-015-1401-9} }
Computational Biomechanics for Patient-Specific Applications.	Miller, K.	2016	Annals of Biomedical Engineering, vol. 44(1), pp. 1-2	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2016janmillermillerABEcomputational, author = {Miller, Karol}, title = {Computational Biomechanics for Patient-Specific Applications.}, journal = {Annals of Biomedical Engineering}, school = {University of Luxembourg, Luxembourg, Luxembourg. [email protected].}, year = {2016}, volume = {44}, number = {1}, pages = {1--2}, doi = {10.1007/s10439-015-1519-9} }
Modelling the Presence of Diffuse Axonal Injury in Primary Phase Blast-Induced Traumatic Brain Injury	Sinclair, M., Wittek, A., Doyle, B., Miller, K. and Joldes, G.R.	2016	Computational Biomechanics for Medicine, pp. 195-203, Springer International Publishing	bookchapter	[BibTeX]
BibTeX: @bookchapter{2016sinclairjoldesmodelling, author = {Sinclair, Matthew and Wittek, Adam and Doyle, Barry and Miller, Karol and Joldes, Grand R}, title = {Modelling the Presence of Diffuse Axonal Injury in Primary Phase Blast-Induced Traumatic Brain Injury}, booktitle = {Computational Biomechanics for Medicine}, publisher = {Springer International Publishing}, year = {2016}, pages = {195--203} }
On the appropriateness of modelling brain parenchyma as a biphasic continuum	Tavner, A., Roy, T.D., Hor, K., Majimbi, M., Joldes, G., Wittek, A., Bunt, S. and Miller, K.	2016	Journal of the mechanical behavior of biomedical materials, vol. 61, pp. 511-518, Elsevier	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2016tavnermillerJotmbobmappropriateness, author = {Tavner, ACR and Roy, T Dutta and Hor, KWW and Majimbi, M and Joldes, GR and Wittek, A and Bunt, S and Miller, K}, title = {On the appropriateness of modelling brain parenchyma as a biphasic continuum}, journal = {Journal of the mechanical behavior of biomedical materials}, publisher = {Elsevier}, year = {2016}, volume = {61}, pages = {511--518}, doi = {10.1016/j.jmbbm.2016.04.010} }
Numerical investigations of rib fracture failure models in different dynamic loading conditions. [Abstract]	Wang, F., Yang, J., Miller, K., Li, G., Joldes, G.R., Doyle, B. and Wittek, A.	2016	Computer Methods in Biomechanics and Biomedical Engineering, vol. 19(5), pp. 527-537	article	[BibTeX] [PDF] [DOI]
Abstract: Rib fracture is one of the most common thoracic injuries in vehicle traffic accidents that can result in fatalities associated with seriously injured internal organs. A failure model is critical when modelling rib fracture to predict such injuries. Different rib failure models have been proposed in prediction of thorax injuries. However, the biofidelity of the fracture failure models when varying the loading conditions and the effects of a rib fracture failure model on prediction of thoracic injuries have been studied only to a limited extent. Therefore, this study aimed to investigate the effects of three rib failure models on prediction of thoracic injuries using a previously validated finite element model of the human thorax. The performance and biofidelity of each rib failure model were first evaluated by modelling rib responses to different loading conditions in two experimental configurations: (1) the three-point bending on the specimen taken from rib and (2) the anterior-posterior dynamic loading to an entire bony part of the rib. Furthermore, the simulation of the rib failure behaviour in the frontal impact to an entire thorax was conducted at varying velocities and the effects of the failure models were analysed with respect to the severity of rib cage damages. Simulation results demonstrated that the responses of the thorax model are similar to the general trends of the rib fracture responses reported in the experimental literature. However, they also indicated that the accuracy of the rib fracture prediction using a given failure model varies for different loading conditions.
BibTeX: @article{2016wangwittekCMBBEnumerical, author = {Wang, Fang and Yang, Jikuang and Miller, Karol and Li, Guibing and Joldes, Grand R and Doyle, Barry and Wittek, Adam}, title = {Numerical investigations of rib fracture failure models in different dynamic loading conditions.}, journal = {Computer Methods in Biomechanics and Biomedical Engineering}, school = {c Intelligent Systems for Medicine Laboratory, School of Mechanical and Chemical Engineering, The University of Western Australia , Crawley-Perth 6009 , Australia.}, year = {2016}, volume = {19}, number = {5}, pages = {527--537}, doi = {10.1080/10255842.2015.1043905} }
From Finite Element Meshes to Clouds of Points: A Review of Methods for Generation of Computational Biomechanics Models for Patient-Specific Applications	Wittek, A., Grosland, N.M., Joldes, G.R., Magnotta, V. and Miller, K.	2016	Annals of Biomedical Engineering, vol. 44(1), pp. 3-15	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2016janwittekmillerAoBEfinite, author = {Wittek, Adam and Grosland, Nicole M. and Joldes, Grand Roman and Magnotta, Vincent and Miller, Karol}, title = {From Finite Element Meshes to Clouds of Points: A Review of Methods for Generation of Computational Biomechanics Models for Patient-Specific Applications}, journal = {Annals of Biomedical Engineering}, year = {2016}, volume = {44}, number = {1}, pages = {3--15}, doi = {10.1007/s10439-015-1469-2} }
Mechanical Properties of Brain–Skull Interface in Compression [Abstract]	Agrawal, S., Wittek, A., Joldes, G., Bunt, S. and Miller, K.	2015	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [PDF] [DOI]
Abstract: This study investigated mechanical properties of brain–skull interface, important for surgery simulation and injury biomechanics. Direct examination of brain–skull interface is difficult due to its delicate nature and complex geometry that follows the skull and brain surface. Hence, we conducted uniaxial compression tests on samples containing skull, meninges and brain. We combined sophisticated measurement data with non-linear finite element analysis to obtain the properties of brain–skull interface. Skull was considered a rigid object as forces obtained were very small to induce any measurable deformation on it. Surface contact model between brain and skull was used to simulate the brain–skull interface. Good correlation between sample deformation in experiment and simulation was used to confirm the brain–skull interface property.
BibTeX: @bookchapter{2015janagrawalmillerCBfMmechanical, author = {Agrawal, Sudip and Wittek, Adam and Joldes, Grand and Bunt, Stuart and Miller, Karol}, title = {Mechanical Properties of Brain–Skull Interface in Compression}, journal = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2015}, doi = {10.1007/978-3-319-15503-6_8} }
Multi-scale fracture, model reduction, CAD and image as a model	Bordas, S., Kerfriden, P., Beex, L., Atroshchenko, E. and Miller, K.	2015	“Advanced Problems in Mechanics” The International Conference	inproceedings	[BibTeX]
BibTeX: @inproceedings{2015bordasmillermulti, author = {Bordas, Stéphane and Kerfriden, Pierre and Beex, Lars and Atroshchenko, Elena and Miller, Karol}, title = {Multi-scale fracture, model reduction, CAD and image as a model}, booktitle = {“Advanced Problems in Mechanics” The International Conference}, year = {2015} }
Implementation of a Modified Moving Least Squares Approximation for Predicting Soft Tissue Deformation Using a Meshless Method [Abstract]	Chowdhury, H.A., Joldes, G.R., Wittek, A., Doyle, B., Pasternak, E. and Miller, K.	2015	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: In applications where the organic soft tissue undergoes large deformations, traditional finite element methods can fail due to element distortion. In this context, meshless methods, which require no mesh for defining the interpolation field, can offer stable solutions. In meshless method, the moving least square (MLS) shape functions have been widely used for approximating the unknown field functions using the scattered field nodes. However, the classical MLS places strict requirements on the nodal distributions inside the support domain in order to maintain the non-singularity of the moment matrix. These limitations are preventing the practical use of higher order polynomial basis in classical MLS for randomly distributed nodes despite their capability for more accurate approximation of complex deformation fields. A modified moving least squares (MMLS) approximation has been recently developed by ISML. This paper assesses the interpolation capabilities of the MMLS. The proposed meshless method based on MMLS is used for computing the extension of a soft tissue sample and for a brain deformation simulation in 2D. The results are compared with the commercial finite element software ABAQUS. The simulation results demonstrate the superior performance of the MMLS over classical MLS with linear basis functions in terms of accuracy of the solution.
BibTeX: @bookchapter{2015janchowdhurymillerCBfMimplementation, author = {Chowdhury, Habibullah Amin and Joldes, Grand Roman and Wittek, Adam and Doyle, Barry and Pasternak, Elena and Miller, Karol}, title = {Implementation of a Modified Moving Least Squares Approximation for Predicting Soft Tissue Deformation Using a Meshless Method}, journal = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2015}, doi = {10.1007/978-3-319-15503-6_6} }
A Meshless Method Based on the Modified Moving Least Squares for Computing Soft Tissue Deformation	Chowdhury, H., Joldes, G., Wittek, A., Doyle, B., Pasternak, E. and Miller, K.	2015	4th International Conference on Computational and Mathematical Biomedical Engineering, pp. 328-331	inproceedings	[BibTeX]
BibTeX: @inproceedings{2015chowdhurymillermeshless, author = {Chowdhury, H. and Joldes, G.R. and Wittek, A. and Doyle, B.J. and Pasternak, E. and Miller, K.}, title = {A Meshless Method Based on the Modified Moving Least Squares for Computing Soft Tissue Deformation}, booktitle = {4th International Conference on Computational and Mathematical Biomedical Engineering}, year = {2015}, pages = {328--331} }
Computational Biomechanics for Medicine	Doyle, B. Miller, K., Wittek, A. and Nielsen, P.M. (Eds)	2015	Springer International Publishing, Cham	book	[BibTeX] [DOI]
BibTeX: @book{2015doyledoylecomputational, author = {Barry Doyle}, title = {Computational Biomechanics for Medicine}, publisher = {Springer International Publishing}, year = {2015}, doi = {10.1007/978-3-319-15503-6} }
Towards measuring neuroimage misalignment. [Abstract]	Garlapati, R.R., Mostayed, A., Joldes, G.R., Wittek, A., Doyle, B. and Miller, K.	2015	Computers in Biology and Medicine, vol. 64, pp. 12-23	article	[BibTeX] [PDF] [DOI]
Abstract: To enhance neuro-navigation, high quality pre-operative images must be registered onto intra-operative configuration of the brain. Therefore evaluation of the degree to which structures may remain misaligned after registration is critically important. We consider two Hausdorff Distance (HD)-based evaluation approaches: the edge-based HD (EBHD) metric and the Robust HD (RHD) metric as well as various commonly used intensity-based similarity metrics such as Mutual Information (MI), Normalised Mutual Information (NMI), Entropy Correlation Coefficient (ECC), Kullback-Leibler Distance (KLD) and Correlation Ratio (CR). We conducted the evaluation by applying known deformations to simple sample images and real cases of brain shift. We conclude that the intensity-based similarity metrics such as MI, NMI, ECC, KLD and CR do not correlate well with actual alignment errors, and hence are not useful for assessing misalignment. On the contrary, the EBHD and the RHD metrics correlated well with actual alignment errors; however, they have been found to underestimate the actual misalignment. We also note that it is beneficial to present HD results as a percentile-HD curve rather than a single number such as the 95-percentile HD. Percentile-HD curves present the full range of alignment errors and also facilitate the comparison of results obtained using different approaches. Furthermore, the qualities that should be possessed by an ideal evaluation metric were highlighted. Future studies could focus on developing such an evaluation metric.
BibTeX: @article{2015sepgarlapatimillerCBMtowards, author = {Garlapati, Revanth Reddy and Mostayed, Ahmed and Joldes, Grand Roman and Wittek, Adam and Doyle, Barry and Miller, Karol}, title = {Towards measuring neuroimage misalignment.}, journal = {Computers in Biology and Medicine}, school = {Intelligent Systems for Medicine Laboratory, The University of Western Australia, Perth, Australia; Institute of Mechanics and Advanced Materials, School of Engineering, Cardiff University, Cardiff, Wales, United Kingdom. Electronic address: [email protected].}, year = {2015}, volume = {64}, pages = {12--23}, doi = {10.1016/j.compbiomed.2015.06.003} }
Students’ responses to authentic assessment designed to develop commitment to performing at their best	Guzzomi, A.L., Male, S.A. and Miller, K.	2015	European Journal of Engineering Education, pp. 10-1080	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2015guzzomimillerEJoEEstudents, author = {Guzzomi, Andrew L. and Male, Sally A. and Miller, Karol}, title = {Students’ responses to authentic assessment designed to develop commitment to performing at their best}, journal = {European Journal of Engineering Education}, year = {2015}, pages = {10--1080}, doi = {10.1080/03043797.2015.1121465} }
Efficient visibility criterion for discontinuities discretised by triangular surface meshes	Holgate, N., Joldes, G.R. and Miller, K.	2015	Engineering Analysis with Boundary Elements, vol. 58, pp. 1-6, Elsevier	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2015holgatemillerEAwBEefficient, author = {Holgate, Nicholas and Joldes, Grand Roman and Miller, Karol}, title = {Efficient visibility criterion for discontinuities discretised by triangular surface meshes}, journal = {Engineering Analysis with Boundary Elements}, publisher = {Elsevier}, year = {2015}, volume = {58}, pages = {1--6}, doi = {10.1016/j.enganabound.2015.02.014} }
Modified Moving Least Squares with Polynomial Bases for Scattered Data Approximation	Joldes, G.R., Chowdhury, H.A., Wittek, A., Doyle, B. and Miller, K.	2015	Applied Mathematics and Computation, vol. 266, pp. 893-902, Elsevier	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2015joldesmillerAMaCmodified, author = {Joldes, Grand Roman and Chowdhury, Habibullah Amin and Wittek, Adam and Doyle, Barry and Miller, Karol}, title = {Modified Moving Least Squares with Polynomial Bases for Scattered Data Approximation}, journal = {Applied Mathematics and Computation}, publisher = {Elsevier}, year = {2015}, volume = {266}, pages = {893--902}, doi = {10.1016/j.amc.2015.05.150} }
A total lagrangian based method for recovering the un-deformed configuration in finite elasticity	Joldes, G.R., Wittek, A. and Miller, K.	2015	Applied Mathematical Modelling, vol. 39(14), pp. 3913-3923, Elsevier	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2015joldesmillerAMMtotal, author = {Joldes, Grand Roman and Wittek, Adam and Miller, Karol}, title = {A total lagrangian based method for recovering the un-deformed configuration in finite elasticity}, journal = {Applied Mathematical Modelling}, publisher = {Elsevier}, year = {2015}, volume = {39}, number = {14}, pages = {3913--3923}, doi = {10.1016/j.apm.2014.12.013} }
Adaptive numerical integration in Element-Free Galerkin methods for elliptic boundary value problems	Joldes, G.R., Wittek, A. and Miller, K.	2015	Engineering Analysis with Boundary Elements, vol. 51, pp. 52-63, Elsevier	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2015joldesmillerEAwBEadaptive, author = {Joldes, Grand Roman and Wittek, Adam and Miller, Karol}, title = {Adaptive numerical integration in Element-Free Galerkin methods for elliptic boundary value problems}, journal = {Engineering Analysis with Boundary Elements}, publisher = {Elsevier}, year = {2015}, volume = {51}, pages = {52--63}, doi = {10.1016/j.enganabound.2014.10.007} }
The Impact of Minor Downstream Arteries on Upstream Haemodynamics: An Iliac Aneurysm Case Study	Kelsey, L., Norman, P., Powell, J., Miller, K. and Doyle, B.J.	2015	4th International Conference on Computational and Mathematical Biomedical Engineering, pp. 794-797	inproceedings	[BibTeX]
BibTeX: @inproceedings{2015kelseydoyleimpact, author = {Kelsey, L. and Norman, P.E. and Powell, J.T. and Miller, K. and B.J., Doyle}, title = {The Impact of Minor Downstream Arteries on Upstream Haemodynamics: An Iliac Aneurysm Case Study}, booktitle = {4th International Conference on Computational and Mathematical Biomedical Engineering}, year = {2015}, pages = {794--797} }
Patient-specific biomechanical model as whole-body CT image registration tool. [Abstract]	Li, M., Miller, K., Joldes, G.R., Doyle, B., Garlapati, R.R., Kikinis, R. and Wittek, A.	2015	Medical Image Analysis, vol. 22(1), pp. 22-34	article	[BibTeX] [PDF] [DOI]
Abstract: Whole-body computed tomography (CT) image registration is important for cancer diagnosis, therapy planning and treatment. Such registration requires accounting for large differences between source and target images caused by deformations of soft organs/tissues and articulated motion of skeletal structures. The registration algorithms relying solely on image processing methods exhibit deficiencies in accounting for such deformations and motion. We propose to predict the deformations and movements of body organs/tissues and skeletal structures for whole-body CT image registration using patient-specific non-linear biomechanical modelling. Unlike the conventional biomechanical modelling, our approach for building the biomechanical models does not require time-consuming segmentation of CT scans to divide the whole body into non-overlapping constituents with different material properties. Instead, a Fuzzy C-Means (FCM) algorithm is used for tissue classification to assign the constitutive properties automatically at integration points of the computation grid. We use only very simple segmentation of the spine when determining vertebrae displacements to define loading for biomechanical models. We demonstrate the feasibility and accuracy of our approach on CT images of seven patients suffering from cancer and aortic disease. The results confirm that accurate whole-body CT image registration can be achieved using a patient-specific non-linear biomechanical model constructed without time-consuming segmentation of the whole-body images.
BibTeX: @article{2015mayliwittekMIApatient, author = {Li, Mao and Miller, Karol and Joldes, Grand Roman and Doyle, Barry and Garlapati, Revanth Reddy and Kikinis, Ron and Wittek, Adam}, title = {Patient-specific biomechanical model as whole-body CT image registration tool.}, journal = {Medical Image Analysis}, school = {Intelligent Systems for Medicine Laboratory, School of Mechanical and Chemical Engineering, The University of Western Australia, Crawley, Perth, Australia. Electronic address: [email protected].}, year = {2015}, volume = {22}, number = {1}, pages = {22--34}, doi = {10.1016/j.media.2014.12.008} }
Numerical Algorithm for Simulation of Soft Tissue Swelling and Shrinking in a Total Lagrangian Explicit Dynamics Framework [Abstract]	Zwick, B., Joldes, G.R., Wittek, A. and Miller, K.	2015	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: We present an algorithm for modelling swelling and shrinking of soft tissues based on the total Lagrangian formulation of the finite element (FE) method. Explicit time integration with adaptive dynamic relaxation is used to compute the steady state solution. The algorithm can easily handle geometric and material nonlinearities, and is very efficient because it allows pre-computation of important solution parameters and does not require solution of large systems of equations. Swelling and shrinking behaviour is modelled by applying a multiplicative decomposition of the deformation gradient to separate the total deformation into swelling/shrinking and elastic components. A hyperelastic constitutive law is used to model the elastic behaviour of the material. Accuracy of the algorithm is confirmed by successful verification against an established FE code. The algorithm involves only vector operations and is well suited for parallel implementation for increased computational speed.
BibTeX: @bookchapter{2015janzwickmillerCBfMnumerical, author = {Zwick, Benjamin and Joldes, Grand Roman and Wittek, Adam and Miller, Karol}, title = {Numerical Algorithm for Simulation of Soft Tissue Swelling and Shrinking in a Total Lagrangian Explicit Dynamics Framework}, journal = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2015}, doi = {10.1007/978-3-319-15503-6_4} }
Computational Biomechanics for Medicine	Doyle, B. Miller, K., Wittek, A. and Nielsen, P.M. (Eds)	2014	Springer New York, New York, NY	book	[BibTeX] [DOI]
BibTeX: @book{2014doyledoylecomputational, author = {Barry Doyle}, title = {Computational Biomechanics for Medicine}, publisher = {Springer New York}, year = {2014}, doi = {10.1007/978-1-4939-0745-8} }
From Detection to Rupture: A Serial Computational Fluid Dynamics Case Study of a Rapidly Expanding, Patient-Specific, Ruptured Abdominal Aortic Aneurysm [Abstract]	Doyle, B.J., McGloughlin, T.M., Kavanagh, E.G. and Hoskins, P.R.	2014	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: Computational hemodynamic studies of abdominal aortic aneurysm (AAA) can help elucidate the mechanisms responsible for growth and development. The aim of this work is to determine if AAAs expand and develop intraluminal thrombus (ILT) in regions of low wall shear stress (WSS) predicted with computational fluid dynamics (CFD). Computed tomography (CT) data of an AAA was acquired at four time-points over 2.5 years, from the time of detection to immediately prior to rupture. We used 3D unsteady, laminar, CFD models to investigate the hemodynamics at each time-point. Our three-dimensional reconstructions showed that the primary region of expansion was in the proximal lobe, which not only coincided with the main region of low time-averaged WSS (TAWSS) in our CFD simulations, but also with the development of ILT in vivo. Interestingly, this region was also the rupture location. This is the first serial computational study of an AAA and the work has shown the potential of CFD to model the changing hemodynamics and the relation with ILT development and AAA growth.
BibTeX: @bookchapter{2014jandoylehoskinsdetection, author = {Doyle, Barry J. and McGloughlin, Timothy M. and Kavanagh, Eamon G. and Hoskins, Peter R.}, title = {From Detection to Rupture: A Serial Computational Fluid Dynamics Case Study of a Rapidly Expanding, Patient-Specific, Ruptured Abdominal Aortic Aneurysm}, booktitle = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2014}, doi = {10.1007/978-1-4939-0745-8_5} }
Regions of High Wall Stress Can Predict the Future Location of Rupture of Abdominal Aortic Aneurysm [Abstract]	Doyle, B.J., McGloughlin, T.M., Miller, K., Powell, J.T. and Norman, P.E.	2014	CardioVascular and Interventional Radiology, vol. 37(3), pp. 815, Springer	article	[BibTeX] [PDF] [DOI]
Abstract: Predicting the wall stress in abdominal aortic aneurysm (AAA) using computational modeling may be a useful adjunct to traditional clinical parameters that indicate the risk of rupture. Maximum diameter has been shown to have many limitations, and using current technology it is possible to provide a patient-specific computational risk assessment using routinely acquired medical images. We present a case of AAA rupture where the exact rupture point was clearly visible on the computed tomography (CT) images. A blind computational study based on CT scans acquired 4 months earlier predicted elevated wall stresses in the same region that later experienced rupture.
BibTeX: @article{2014jundoylenormanCaIRregions, author = {Doyle, Barry J. and McGloughlin, Timothy M. and Miller, Karol and Powell, Janet T. and Norman, Paul E.}, title = {Regions of High Wall Stress Can Predict the Future Location of Rupture of Abdominal Aortic Aneurysm}, journal = {CardioVascular and Interventional Radiology}, publisher = {Springer}, year = {2014}, volume = {37}, number = {3}, pages = {815}, doi = {10.1007/s00270-014-0864-7} }
More accurate neuronavigation data provided by biomechanical modeling instead of rigid registration. [Abstract]	Garlapati, R.R., Roy, A., Joldes, G.R., Wittek, A., Mostayed, A., Doyle, B., Warfield, S.K., Kikinis, R., Knuckey, N., Bunt, S. and Miller, K.	2014	Journal of Neurosurgery, vol. 120(6), pp. 1477-1483	article	[BibTeX] [PDF] [DOI]
Abstract: It is possible to improve neuronavigation during image-guided surgery by warping the high-quality preoperative brain images so that they correspond with the current intraoperative configuration of the brain. In this paper, the accuracy of registration results obtained using comprehensive biomechanical models is compared with the accuracy of rigid registration, the technology currently available to patients. This comparison allows investigation into whether biomechanical modeling provides good-quality image data for neuronavigation for a larger proportion of patients than rigid registration. Preoperative images for 33 neurosurgery cases were warped onto their respective intraoperative configurations using both the biomechanics-based method and rigid registration. The Hausdorff distance-based evaluation process, which measures the difference between images, was used to quantify the performance of both registration methods. A statistical test for difference in proportions was conducted to evaluate the null hypothesis that the proportion of patients for whom improved neuronavigation can be achieved is the same for rigid and biomechanics-based registration. The null hypothesis was confidently rejected (p < 10(-4)). Even the modified hypothesis that fewer than 25% of patients would benefit from the use of biomechanics-based registration was rejected at a significance level of 5% (p = 0.02). The biomechanics-based method proved particularly effective in cases demonstrating large craniotomy-induced brain deformations. The outcome of this analysis suggests that nonlinear biomechanics-based methods are beneficial to a large proportion of patients and can be considered for use in the operating theater as a possible means of improving neuronavigation and surgical outcomes.
BibTeX: @article{2014jungarlapatimillerJNmore, author = {Garlapati, Revanth Reddy and Roy, Aditi and Joldes, Grand Roman and Wittek, Adam and Mostayed, Ahmed and Doyle, Barry and Warfield, Simon Keith and Kikinis, Ron and Knuckey, Neville and Bunt, Stuart and Miller, Karol}, title = {More accurate neuronavigation data provided by biomechanical modeling instead of rigid registration.}, journal = {Journal of Neurosurgery}, school = {Intelligent Systems for Medicine Laboratory;}, year = {2014}, volume = {120}, number = {6}, pages = {1477--1483}, doi = {10.3171/2013.12.JNS131165} }
Meshless algorithm for soft tissue cutting in surgical simulation. [Abstract]	Jin, X., Joldes, G.R., Miller, K., Yang, K.H. and Wittek, A.	2014	Computer Methods in Biomechanics and Biomedical Engineering, vol. 17(7), pp. 800-811	article	[BibTeX] [PDF] [DOI]
Abstract: Computation of soft tissue mechanical responses for surgery simulation and image-guided surgery has been dominated by the finite element (FE) method that utilises a mesh of interconnected elements as a computational grid. Shortcomings of such mesh-based discretisation in modelling of surgical cutting include high computational cost and the need for re-meshing in the vicinity of cutting-induced discontinuity. The meshless total Lagrangian adaptive dynamic relaxation (MTLADR) algorithm we present here does not exhibit such shortcomings, as it relies on spatial discretisation in a form of a cloud of nodes. The cutting-induced discontinuity is modelled solely through changes in nodal domains of influence, which is done through efficient implementation of the visibility criterion using the level set method. Accuracy of our MTLADR algorithm with visibility criterion is confirmed against the established nonlinear solution procedures available in the commercial FE code Abaqus.
BibTeX: @article{2014mayjinwittekCMBBEmeshless, author = {Jin, Xia and Joldes, Grand Roman and Miller, Karol and Yang, King H and Wittek, Adam}, title = {Meshless algorithm for soft tissue cutting in surgical simulation.}, journal = {Computer Methods in Biomechanics and Biomedical Engineering}, school = {a Intelligent Systems for Medicine Laboratory, School of Mechanical and Chemical Engineering, University of Western Australia , 35 Stirling Highway, Crawley, Perth , WA 6009 , Australia.}, year = {2014}, volume = {17}, number = {7}, pages = {800--811}, doi = {10.1080/10255842.2012.716829} }
Patient-Specific Meshless Model for Whole-Body Image Registration [Abstract]	Li, M., Miller, K., Joldes, G., Kikinis, R. and Wittek, A.	2014	Biomedical Simulation, Springer	article	[BibTeX] [DOI]
Abstract: Non-rigid registration algorithms that align source and target images play an important role in image-guided surgery and diagnosis. For problems involving large differences between images, such as registration of whole-body radiographic images, biomechanical models have been proposed in recent years. Biomechanical registration has been dominated by Finite Element Method (FEM). In practice, major drawback of FEM is a long time required to generate patient-specific finite element meshes and divide (segment) the image into non-overlapping constituents with different material properties. We eliminate time-consuming mesh generation through application of Meshless Total Lagrangian Explicit Dynamics (MTLED) algorithm that utilises a computational grid in a form of cloud of points. To eliminate the need for segmentation, we use fuzzy tissue classification algorithm to assign the material properties to meshless grid. Comparison of the organ contours in the registered (i.e. source image warped using deformations predicted by our patient-specific meshless model) and target images indicate that our meshless approach facilitates accurate registration of whole-body images with local misalignments of up to only two voxels.
BibTeX: @article{2014janliwittekBSpatient, author = {Li, Mao and Miller, Karol and Joldes, Grand and Kikinis, Ron and Wittek, Adam}, title = {Patient-Specific Meshless Model for Whole-Body Image Registration}, journal = {Biomedical Simulation}, publisher = {Springer}, year = {2014}, doi = {10.1007/978-3-319-12057-7_6} }
Whole-Body Image Registration Using Patient-Specific Nonlinear Finite Element Model [Abstract]	Li, M., Wittek, A., Joldes, G., Zhang, G., Dong, F., Kikinis, R. and Miller, K.	2014	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: Registration of whole-body radiographic images is an important task in analysis of the disease progression and assessment of responses to therapies. Numerous registration algorithms have been successfully used in applications where differences between source and target images are relatively small. However, registration of whole-body CT scans remains extremely challenging for such algorithms as it requires taking large deformations of body organs and articulated skeletal motions into account. For registration problems involving large differences between source and target images, registration using biomechanical models has been recommended in the literature. Therefore, in this study, we propose a patient-specific nonlinear finite element model to predict the movements and deformations of body organs for the whole-body CT image registration. We conducted a verification example in which a patient-specific torso model was implemented using a suite of nonlinear finite element algorithms we previously developed, verified and successfully used in neuroimaging registration. When defining the patient-specific geometry for the generation of computational grid for our model, we abandoned the time-consuming hard segmentation of radiographic images typically used in patient-specific biomechanical modelling to divide the body into non-overlapping constituents with different material properties. Instead, an automated Fuzzy C-Means (FCM) algorithm for tissue classification was applied to assign the constitutive properties at finite element mesh integration points. The loading was defined as a prescribed displacement of the vertebrae (treated as articulated rigid bodies) between the two CT images. Contours of the abdominal organs obtained by warping the source image using the deformation field within the body predicted using our patient-specific finite element model differed by only up to only two voxels from the actual organs’ contours in the target image. These results can be regarded as encouraging step in confirming feasibility of conducting accurate registration of whole-body CT images using nonlinear finite element models without the necessity for time-consuming image segmentation when building patient-specific finite element meshes.
BibTeX: @bookchapter{2014janlimillerCBfMwhole, author = {Li, Mao and Wittek, Adam and Joldes, Grand and Zhang, Guiyong and Dong, Feifei and Kikinis, Ron and Miller, Karol}, title = {Whole-Body Image Registration Using Patient-Specific Nonlinear Finite Element Model}, journal = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2014}, doi = {10.1007/978-1-4939-0745-8_9} }
Efficient inverse isoparametric mapping algorithm for whole-body computed tomography registration using deformations predicted by nonlinear finite element modeling. [Abstract]	Li, M., Wittek, A. and Miller, K.	2014	Journal of Biomechanical Engineering, vol. 136(8)	article	[BibTeX] [PDF] [DOI]
Abstract: Biomechanical modeling methods can be used to predict deformations for medical image registration and particularly, they are very effective for whole-body computed tomography (CT) image registration because differences between the source and target images caused by complex articulated motions and soft tissues deformations are very large. The biomechanics-based image registration method needs to deform the source images using the deformation field predicted by finite element models (FEMs). In practice, the global and local coordinate systems are used in finite element analysis. This involves the transformation of coordinates from the global coordinate system to the local coordinate system when calculating the global coordinates of image voxels for warping images. In this paper, we present an efficient numerical inverse isoparametric mapping algorithm to calculate the local coordinates of arbitrary points within the eight-noded hexahedral finite element. Verification of the algorithm for a nonparallelepiped hexahedral element confirms its accuracy, fast convergence, and efficiency. The algorithm's application in warping of the whole-body CT using the deformation field predicted by means of a biomechanical FEM confirms its reliability in the context of whole-body CT registration.
BibTeX: @article{2014auglimillerJBEefficient, author = {Li, Mao and Wittek, Adam and Miller, Karol}, title = {Efficient inverse isoparametric mapping algorithm for whole-body computed tomography registration using deformations predicted by nonlinear finite element modeling.}, journal = {Journal of Biomechanical Engineering}, year = {2014}, volume = {136}, number = {8}, doi = {10.1115/1.4027667} }
Beyond finite element method: towards robust and accurate meshless method for computational biomechanics for Medicine	Miller, K.	2014	ICCM2014, vol. 1, pp. Plenary-Lecture	inproceedings	[BibTeX]
BibTeX: @inproceedings{2014millermillerfinite, author = {Miller, K.}, title = {Beyond finite element method: towards robust and accurate meshless method for computational biomechanics for Medicine}, booktitle = {ICCM2014}, year = {2014}, volume = {1}, pages = {Plenary--Lecture} }
Modeling Three-Dimensional Avascular Tumor Growth Using Lattice Gas Cellular Automata [Abstract]	Shrestha, S.M.B., Joldes, G., Wittek, A. and Miller, K.	2014	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: We model and simulate avascular tumor growth in three dimensions using lattice gas cellular automata (LGCA). Our 3D models are an advance over current state-of-the-art where most three dimensional (3D) models are in fact only a series of two dimensional models simulated to give an appearance of a 3D model. In our 3D model, we use binary description of cells and their states for computational speed and efficiency. The fate and distribution of cells in our model are determined by the Lattice–Boltzmann energy. We simulate our model in a comparable size of lattice and show that the findings are in good agreement with biological tumor behavior.
BibTeX: @bookchapter{2014janshresthamillerCBfMmodeling, author = {Shrestha, Sachin Man Bajimaya and Joldes, Grand and Wittek, Adam and Miller, Karol}, title = {Modeling Three-Dimensional Avascular Tumor Growth Using Lattice Gas Cellular Automata}, journal = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2014}, doi = {10.1007/978-1-4939-0745-8_2} }
A three-dimensional nonlinear meshfree algorithm for simulating mechanical responses of soft tissue	Zhang, G., Wittek, A., Joldes, G., Jin, X. and Miller, K.	2014	Engineering Analysis with Boundary Elements, vol. 42, pp. 60-66, Elsevier	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2014zhangmillerEAwBEthree, author = {Zhang, GY and Wittek, A and Joldes, GR and Jin, X and Miller, K}, title = {A three-dimensional nonlinear meshfree algorithm for simulating mechanical responses of soft tissue}, journal = {Engineering Analysis with Boundary Elements}, publisher = {Elsevier}, year = {2014}, volume = {42}, pages = {60--66}, doi = {10.1016/j.enganabound.2013.08.014} }
Inverse problems and material identification in tissue biomechanics.	Avril, S., Evans, S. and Miller, K.	2013	Journal of the Mechanical Behavior of Biomedical Materials, vol. 27, pp. 129-131	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2013novavrilmillerJMBBMinverse, author = {Avril, StÃ&circledc;phane and Evans, Sam and Miller, Karol}, title = {Inverse problems and material identification in tissue biomechanics.}, journal = {Journal of the Mechanical Behavior of Biomedical Materials}, year = {2013}, volume = {27}, pages = {129--131}, doi = {10.1016/j.jmbbm.2013.07.001} }
Biomechanical analyses of the thoracic aorta: Could wall stress and 3D geometry help identify patients at risk of acute aortic dissection?	Doyle, B., Hoskins, P., Miller, K., Newby, D. and Dweck, M.	2013	3rd International Conference on Mathematical and Computational Biomedical Engineering (CBME2013),, pp. 148-151	inproceedings	[BibTeX]
BibTeX: @inproceedings{2013doyledweckbiomechanical, author = {Doyle, B.J. and Hoskins, P.R and Miller, K. and Newby, D.E. and M.R. Dweck}, title = {Biomechanical analyses of the thoracic aorta: Could wall stress and 3D geometry help identify patients at risk of acute aortic dissection?}, booktitle = {3rd International Conference on Mathematical and Computational Biomedical Engineering (CBME2013),}, year = {2013}, pages = {148--151} }
Objective Evaluation of Accuracy of Intra-Operative Neuroimage Registration [Abstract]	Garlapati, R.R., Joldes, G.R., Wittek, A., Lam, J., Weisenfeld, N., Hans, A., Warfield, S.K., Kikinis, R. and Miller, K.	2013	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: Pre-operative brain images that are registered onto relevant intra-operative images can enhance navigation during image-guided neurosurgery. One of the crucial steps in the process of image registration is assessment of its accuracy. The accuracy of an image registration procedure was evaluated in one of our previous studies, for five cases of neurosurgery, using a manual segmentation-based method that is subjective and prone to human errors. The aim of this study is to develop an evaluation method that is objective and automatic. An edge-based Hausdorff Distance (HD) metric based on Canny edges was developed for evaluation. Subsequently, the accuracy of non-rigid registration (NRR) results was evaluated using intra-operative images as ground truth and compared with those from the previous study. The obtained results compared well despite the differences in the methods employed. The edge-based HD metric provides an objective measure for image registration accuracy evaluation.
BibTeX: @bookchapter{2013jangarlapatimillerobjective, author = {Garlapati, Revanth Reddy and Joldes, Grand Roman and Wittek, Adam and Lam, Jonathan and Weisenfeld, Neil and Hans, Arne and Warfield, Simon K. and Kikinis, Ron and Miller, Karol}, title = {Objective Evaluation of Accuracy of Intra-Operative Neuroimage Registration}, booktitle = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2013}, doi = {10.1007/978-1-4614-6351-1_9} }
Computational biomechanics of the brain brings real benefits in the operating theatre	Garlapati, R.R., Wittek, A., Mostayed, A., Roy, A. and Miller, K.	2013	3rd International Conference on Computational and Mathematical Biomedical Engineering -- CMBE2013, pp. 71-74	inproceedings	[BibTeX]
BibTeX: @inproceedings{2013garlapatimillercomputational, author = {Garlapati, R. R. and Wittek, A. and Mostayed, A. and Roy, A. and Miller, K.}, title = {Computational biomechanics of the brain brings real benefits in the operating theatre}, booktitle = {3rd International Conference on Computational and Mathematical Biomedical Engineering -- CMBE2013}, year = {2013}, pages = {71--74} }
A mobility assignment with industry relevance [Abstract]	Guzzomi, A.L. and Miller, K.	2013	New Trends in Mechanism and Machine Science, Springer	bookchapter	[BibTeX] [DOI]
Abstract: In an attempt to improve the way students prepare for industry a 3rd year mechanisms and multibody systems class was given an assignment with a non-traditional scope and marking guide. Although the team based assignment, like those of prior years, involved mobility analysis of real historical systems in the form of a formal report, it was proposed that the assignment be marked to industry expectations. This meant 100% if the conclusions were satisfactory and 0% if they were not. This experience produced many interesting outcomes and these are discussed. The paper describes the process that led to the implementation of this new assignment structure. The methodology used in its development and reflections of both the authors and the students are discussed.
BibTeX: @bookchapter{2013janguzzomimillermobility, author = {Guzzomi, A. L. and Miller, K.}, title = {A mobility assignment with industry relevance}, booktitle = {New Trends in Mechanism and Machine Science}, publisher = {Springer}, year = {2013}, doi = {10.1007/978-94-007-4902-3_74} }
3D Algorithm for Simulation of Soft Tissue Cutting [Abstract]	Jin, X., Joldes, G.R., Miller, K. and Wittek, A.	2013	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: Modelling and simulation of soft tissue cutting in 3D remain one of the most challenging problems in surgery simulation, not only because of the nonlinear geometric and material behaviour exhibited by soft tissue but also due to the complexity of introducing the cutting-induced discontinuity. In most publications, the progressive surgical cutting is modelled by conventional finite element (FE) method, in which the high computational cost and error accumulation due to re-meshing constrain the computational efficiency and accuracy. In this paper, a meshless Total Lagrangian Adaptive Dynamic Relaxation (MTLADR) 3D cutting algorithm is proposed to predict the steady-state responses of soft tissue at any stage of surgical cutting in 3D. The MTLADR 3D algorithm features a spatial discretisation using a cloud of nodes. With the benefits of no meshing and no re-meshing, the cutting-induced discontinuity is modelled and simulated by adding nodes on the cutting faces and implementing the visibility criterion with the aid of the level set method. The accuracy of the MTLADR 3D cutting algorithm is verified against the established nonlinear solution procedures available in commercial FE software Abaqus.
BibTeX: @bookchapter{2013janjinwittek3d, author = {Jin, Xia and Joldes, Grand Roman and Miller, Karol and Wittek, Adam}, title = {3D Algorithm for Simulation of Soft Tissue Cutting}, booktitle = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2013}, doi = {10.1007/978-1-4614-6351-1_6} }
Mechanical properties of the brain-skull interface. [Abstract]	Mazumder, M.M.G., Miller, K., Bunt, S., Mostayed, A., Joldes, G., Day, R., Hart, R. and Wittek, A.	2013	Acta of Bioengineering and Biomechanics, vol. 15(2), pp. 3-11	article	[BibTeX] [PDF] [DOI]
Abstract: Knowledge of the mechanical properties of the brain-skull interface is important for surgery simulation and injury biomechanics. These properties are known only to a limited extent. In this study we conducted in situ indentation of the sheep brain, and proposed to derive the macroscopic mechanical properties of the brain-skull interface from the results of these experiments. To the best of our knowledge, this is the first ever analysis of this kind. When conducting in situ indentation of the brain, the reaction force on the indentor was measured. After the indentation, a cylindrical sample of the brain tissue was extracted and subjected to uniaxial compression test. A model of the brain indentation experiment was built in the Finite Element (FE) solver ABAQUS™. In the model, the mechanical properties of the brain tissue were assigned as obtained from the uniaxial compression test and the brain-skull interface was modeled as linear springs. The interface stiffness (defined as sum of stiffnesses of the springs divided by the interface area) was varied to obtain good agreement between the calculated and experimentally measured indentor force-displacement relationship. Such agreement was found to occur for the brain-skull interface stiffness of 11.45 Nmm�¹/mm². This allowed identification of the overall mechanical properties of the brain-skull interface.
BibTeX: @article{2013mazumderwittekABBmechanical, author = {Mazumder, Mohammad Mynuddin Gani and Miller, Karol and Bunt, Stuart and Mostayed, Ahmed and Joldes, Grand and Day, Robert and Hart, Robin and Wittek, Adam}, title = {Mechanical properties of the brain-skull interface.}, journal = {Acta of Bioengineering and Biomechanics}, school = {Intelligent Systems for Medicine Laboratory, University of Western Australia, Australia.}, year = {2013}, volume = {15}, number = {2}, pages = {3--11}, doi = {10.5277/abb130201} }
Computational modelling of hydrocephalus.	Miller, K., Bunt, S. and Wittek, A.	2013	Journal of Biomechanics, vol. 46(14), pp. 2558-2559	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2013sepmillerwittekJBcomputational, author = {Miller, Karol and Bunt, Stuart and Wittek, Adam}, title = {Computational modelling of hydrocephalus.}, journal = {Journal of Biomechanics}, school = {Intelligent Systems for Medicine Laboratory, The University of Western Australia, Crawley/Perth, Western Australia, Australia; Institute of Mechanics and Advanced Materials, Cardiff University, Wales, UK. Electronic address: [email protected].}, year = {2013}, volume = {46}, number = {14}, pages = {2558--2559}, doi = {10.1016/j.jbiomech.2013.07.040} }
On the prospect of patient-specific biomechanics without patient-specific properties of tissues. [Abstract]	Miller, K. and Lu, J.	2013	Journal of the Mechanical Behavior of Biomedical Materials, vol. 27, pp. 154-166, Elsevier	article	[BibTeX] [PDF] [DOI]
Abstract: This paper presents main theses of two keynote lectures delivered at Euromech Colloquium "Advanced experimental approaches and inverse problems in tissue biomechanics" held in Saint Etienne in June 2012. We are witnessing an advent of patient-specific biomechanics that will bring in the future personalized treatments to sufferers all over the world. It is the current task of biomechanists to devise methods for clinically-relevant patient-specific modeling. One of the obstacles standing before the biomechanics community is the difficulty in obtaining patient-specific properties of tissues to be used in biomechanical models. We postulate that focusing on reformulating computational mechanics problems in such a way that the results are weakly sensitive to the variation in mechanical properties of simulated continua is more likely to bear fruit in near future. We consider two types of problems: (i) displacement-zero traction problems whose solutions in displacements are weakly sensitive to mechanical properties of the considered continuum; and (ii) problems that are approximately statically determinate and therefore their solutions in stresses are also weakly sensitive to mechanical properties of constituents. We demonstrate that the kinematically loaded biomechanical models of the first type are applicable in the field of image-guided surgery where the current, intraoperative configuration of a soft organ is of critical importance. We show that sac-like membranes, which are prototypes of many thin-walled biological organs, are approximately statically determinate and therefore useful solutions for wall stress can be obtained without the knowledge of the wall's properties. We demonstrate the clinical applicability and effectiveness of the proposed methods using examples from modeling neurosurgery and intracranial aneurysms.
BibTeX: @article{2013novmillerluJMBBMprospect, author = {Miller, Karol and Lu, Jia}, title = {On the prospect of patient-specific biomechanics without patient-specific properties of tissues.}, journal = {Journal of the Mechanical Behavior of Biomedical Materials}, publisher = {Elsevier}, school = {Intelligent Systems for Medicine Laboratory, School of Mechanical and Chemical Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA 6009, Australia. Electronic address: [email protected].}, year = {2013}, volume = {27}, pages = {154--166}, doi = {10.1016/j.jmbbm.2013.01.013} }
Intra-operative Update of Neuro-images: Comparison of Performance of Image Warping Using Patient-Specific Biomechanical Model and BSpline Image Registration [Abstract]	Mostayed, A., Garlapati, R.R., Joldes, G.R., Wittek, A., Kikinis, R., Warfield, S.K. and Miller, K.	2013	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: This paper compares the warping of neuro-images using brain deformation predicted by means of patient-specific biomechanical model with the neuro-image registration using BSpline-based free form deformation algorithm. Deformation fields obtained from both algorithms are qualitatively compared and overlaps of edges extracted from the images are examined. Finally, an edge-based Hausdorff distance metric is defined to quantitatively evaluate the accuracy of registration for these two algorithms. From the results it is concluded that the patient-specific biomechanical model ensures higher registration accuracy than the BSpline registration algorithm.
BibTeX: @bookchapter{2013janmostayedmillerintra, author = {Mostayed, Ahmed and Garlapati, Revanth Reddy and Joldes, Grand Roman and Wittek, Adam and Kikinis, Ron and Warfield, Simon K. and Miller, Karol}, title = {Intra-operative Update of Neuro-images: Comparison of Performance of Image Warping Using Patient-Specific Biomechanical Model and BSpline Image Registration}, booktitle = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2013}, doi = {10.1007/978-1-4614-6351-1_12} }
Biomechanical Model as a Registration Tool for Image-Guided Neurosurgery: Evaluation Against BSpline Registration [Abstract]	Mostayed, A., Garlapati, R.R., Joldes, G.R., Wittek, A., Roy, A., Kikinis, R., Warfield, S.K. and Miller, K.	2013	Annals of Biomedical Engineering, vol. 41(11), pp. 2409, Springer	article	[BibTeX] [PDF] [DOI]
Abstract: In this paper we evaluate the accuracy of warping of neuro-images using brain deformation predicted by means of a patient-specific biomechanical model against registration using a BSpline-based free form deformation algorithm. Unlike the BSpline algorithm, biomechanics-based registration does not require an intra-operative MR image which is very expensive and cumbersome to acquire. Only sparse intra-operative data on the brain surface is sufficient to compute deformation for the whole brain. In this contribution the deformation fields obtained from both methods are qualitatively compared and overlaps of Canny edges extracted from the images are examined. We define an edge based Hausdorff distance metric to quantitatively evaluate the accuracy of registration for these two algorithms. The qualitative and quantitative evaluations indicate that our biomechanics-based registration algorithm, despite using much less input data, has at least as high registration accuracy as that of the BSpline algorithm.
BibTeX: @article{2013novmostayedmillerAoBEbiomechanical, author = {Mostayed, Ahmed and Garlapati, Revanth Reddy and Joldes, Grand Roman and Wittek, Adam and Roy, Aditi and Kikinis, Ron and Warfield, Simon K. and Miller, Karol}, title = {Biomechanical Model as a Registration Tool for Image-Guided Neurosurgery: Evaluation Against BSpline Registration}, journal = {Annals of Biomedical Engineering}, publisher = {Springer}, year = {2013}, volume = {41}, number = {11}, pages = {2409}, doi = {10.1007/s10439-013-0838-y} }
Cellular automata coupled with steady-state nutrient solution permit simulation of large-scale growth of tumours. [Abstract]	Shrestha, S.M.B., Joldes, G.R., Wittek, A. and Miller, K.	2013	International Journal for Numerical Methods in Biomedical Engineering, vol. 29(4), pp. 542-559	article	[BibTeX] [PDF] [DOI]
Abstract: We model complete growth of an avascular tumour by employing cellular automata for the growth of cells and steady-state equation to solve for nutrient concentrations. Our modelling and computer simulation results show that, in the case of a brain tumour, oxygen distribution in the tumour volume may be sufficiently described by a time-independent steady-state equation without losing the characteristics of a time-dependent diffusion equation. This makes the solution of oxygen concentration in the tumour volume computationally more efficient, thus enabling simulation of tumour growth on a large scale. We solve this steady-state equation using a central difference method. We take into account the composition of cells and intercellular adhesion in addition to processes involved in cell cycle--proliferation, quiescence, apoptosis, and necrosis--in the tumour model. More importantly, we consider cell mutation that gives rise to different phenotypes and therefore a tumour with heterogeneous population of cells. A new phenotype is probabilistically chosen and has the ability to survive at lower levels of nutrient concentration and reproduce faster. We show that heterogeneity of cells that compose a tumour leads to its irregular growth and that avascular growth is not supported for tumours of diameter above 18 mm. We compare results from our growth simulation with existing experimental data on Ehrlich ascites carcinoma and tumour spheroid cultures and show that our results are in good agreement with the experimental findings.
BibTeX: @article{2013aprshresthamillerIJNMBEcellular, author = {Shrestha, Sachin Man Bajimaya and Joldes, Grand Roman and Wittek, Adam and Miller, Karol}, title = {Cellular automata coupled with steady-state nutrient solution permit simulation of large-scale growth of tumours.}, journal = {International Journal for Numerical Methods in Biomedical Engineering}, school = {Intelligent Systems for Medicine Laboratory, The University of Western Australia, Crawley, Western Australia 6009, Australia.}, year = {2013}, volume = {29}, number = {4}, pages = {542--559}, doi = {10.1002/cnm.2539} }
Computational Biomechanics for Medicine	Wittek, A. Miller, K. and Nielsen, P.M. (Eds)	2013	Springer, New York, NY	book	[BibTeX] [DOI]
BibTeX: @book{2013wittekwittekcomputational, author = {Adam Wittek}, title = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2013}, doi = {10.1007/978-1-4614-6351-1} }
Patient-specific computational biomechanics of the brain without segmentation and meshing. [Abstract]	Zhang, J.Y., Joldes, G.R., Wittek, A. and Miller, K.	2013	International Journal for Numerical Methods in Biomedical Engineering, vol. 29(2), pp. 293-308	article	[BibTeX] [PDF] [DOI]
Abstract: Motivated by patient-specific computational modelling in the context of image-guided brain surgery, we propose a new fuzzy mesh-free modelling framework. The method works directly on an unstructured cloud of points that do not form elements so that mesh generation is not required. Mechanical properties are assigned directly to each integration point based on fuzzy tissue classification membership functions without the need for image segmentation. Geometric integration is performed over an underlying uniform background grid. The verification example shows that, while requiring no hard segmentation and meshing, the proposed model gives, for all practical purposes, equivalent results to a finite element model.
BibTeX: @article{2013febzhangmillerIJNMBEpatient, author = {Zhang, Johnny Y and Joldes, Grand Roman and Wittek, Adam and Miller, Karol}, title = {Patient-specific computational biomechanics of the brain without segmentation and meshing.}, journal = {International Journal for Numerical Methods in Biomedical Engineering}, school = {Intelligent Systems for Medicine Laboratory, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.}, year = {2013}, volume = {29}, number = {2}, pages = {293--308}, doi = {10.1002/cnm.2507} }
2-D MESHLESS ALGORITHM FOR MODELLING OF SOFT TISSUE UNDERGOING FRAGMENTATION AND LARGE DEFORMATION: VERIFICATION AND PERFORMANCE EVALUATION	Jin, X., Zhang, G., Joldes, G.R., King., H and Wittek, A.	2012	Proceedings of10th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering., pp. 327-332	inproceedings	[BibTeX]
BibTeX: @inproceedings{2012xiajinxiajin2, author = {Xia Jin, Guiyong Zhang, Grand. R. Joldes, King. H, Adam Wittek}, title = {2-D MESHLESS ALGORITHM FOR MODELLING OF SOFT TISSUE UNDERGOING FRAGMENTATION AND LARGE DEFORMATION: VERIFICATION AND PERFORMANCE EVALUATION}, booktitle = {Proceedings of10th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering.}, year = {2012}, pages = {327--332} }
Stable time step estimates for mesh-free particle methods	Joldes, G.R., Wittek, A. and Miller, K.	2012	International journal for numerical methods in engineering, vol. 91(4), pp. 450-456, John Wiley & Sons, Ltd	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2012joldesmillerIjfnmiestable, author = {Joldes, Grand Roman and Wittek, Adam and Miller, Karol}, title = {Stable time step estimates for mesh-free particle methods}, journal = {International journal for numerical methods in engineering}, publisher = {John Wiley & Sons, Ltd}, year = {2012}, volume = {91}, number = {4}, pages = {450--456}, doi = {10.1002/nme.4290} }
Performing Brain Image Warping Using the Deformation Field Predicted by a Biomechanical Model [Abstract]	Joldes, G.R., Wittek, A., Warfield, S.K. and Miller, K.	2012	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: Biomechanical modeling has become a viable alternative to purely image-based approaches for predicting brain deformation during surgery. Most of the time, a finite element mesh is used for computing the deformation field. Although many papers discuss methods for obtaining the deformation field, there is little information on how it will be used, especially for updating images intraoperatively. In this paper, we discuss some requirements related to the use of this deformation field for warping high quality preoperative brain images. A software implementation is presented, which satisfies most of these requirements. Based on this implementation, we outline some of the difficulties in performing brain registration intraoperatively in real time and propose possible solutions.
BibTeX: @bookchapter{2012janjoldesmillerCBfMperforming, author = {Joldes, Grand Roman and Wittek, Adam and Warfield, Simon K. and Miller, Karol}, title = {Performing Brain Image Warping Using the Deformation Field Predicted by a Biomechanical Model}, journal = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2012}, doi = {10.1007/978-1-4614-3172-5_10} }
TOWARDS DETERMINING MECHANICAL PROPERTIES OF THE BRAIN-SKULL INTERFACE: A STUDY USING BRAIN INDENTATION EXPERIMENT AND MODELLING	M. Mazumder A. Wittek, A.M.G.J.R.H. and Miller, K.	2012	Proceedings of10th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering., pp. 942-947	inproceedings	[BibTeX]
BibTeX: @inproceedings{2012m.mazumdermillertowards, author = {M. Mazumder, A. Wittek, A. Mostayed, G.R. Joldes, R. Hart and K. Miller}, title = {TOWARDS DETERMINING MECHANICAL PROPERTIES OF THE BRAIN-SKULL INTERFACE: A STUDY USING BRAIN INDENTATION EXPERIMENT AND MODELLING}, booktitle = {Proceedings of10th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering.}, year = {2012}, pages = {942--947} }
Beyond finite elements: A comprehensive, patient-specific neurosurgical simulation utilizing a meshless method	Miller, K., Horton, A., Joldes, G. and Wittek, A.	2012	Journal of Biomechanics, vol. 45(15), pp. 2698-2701, Elsevier	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2012millerwittekJobfinite, author = {Miller, K and Horton, A and Joldes, GR and Wittek, A}, title = {Beyond finite elements: A comprehensive, patient-specific neurosurgical simulation utilizing a meshless method}, journal = {Journal of Biomechanics}, publisher = {Elsevier}, year = {2012}, volume = {45}, number = {15}, pages = {2698--2701}, doi = {10.1016/j.jbiomech.2012.07.031} }
Computational Biomechanics for Medicine	Nielsen, P.M. Wittek, A. and Miller, K. (Eds)	2012	Springer New York, New York, NY	book	[BibTeX] [DOI]
BibTeX: @book{2012nielsennielsencomputational, author = {Poul M.F. Nielsen}, title = {Computational Biomechanics for Medicine}, publisher = {Springer New York}, year = {2012}, doi = {10.1007/978-1-4614-3172-5} }
Modeling Heterogeneous Tumor Growth Using Hybrid Cellular Automata [Abstract]	Shrestha, S.M.B., Joldes, G., Wittek, A. and Miller, K.	2012	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: We show that heterogeneity of cells that compose a tumor leads to its irregular growth. We model avascular tumor growth using cellular automata (CA). In our model, we take into account the composition of cells and intercellular adhesion in addition to processes involved in cell cycle—proliferation, quiescence, apoptosis and necrosis. More importantly, we consider cell mutation that gives rise to a different phenotype and therefore, a tumor with heterogeneous population of cells. A new phenotype is probabilistically chosen and has the ability to survive at lower levels of nutrient concentration and reproduce faster. We solve diffusion equation using central difference method to determine the concentration of nutrients, in particular, oxygen available to each cell during the growth process. We present the growth simulation and demonstrate similarity with theoretical findings.
BibTeX: @bookchapter{2012janshresthamillerCBfMmodeling, author = {Shrestha, Sachin Man Bajimaya and Joldes, Grand and Wittek, Adam and Miller, Karol}, title = {Modeling Heterogeneous Tumor Growth Using Hybrid Cellular Automata}, journal = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2012}, doi = {10.1007/978-1-4614-3172-5_14} }
Neuroimage as a Biomechanical Model: Toward New Computational Biomechanics of the Brain [Abstract]	Zhang, J.Y., Joldes, G.R., Wittek, A., Horton, A., Warfield, S.K. and Miller, K.	2012	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: In recent years, predicting brain deformations during surgery using methods of computational biomechanics has become a viable alternative to purely image-based techniques. However, the difficulties with patient-specific computational grid generation prevent the widespread application of biomechanical modeling in medicine. For more efficient computational grid generation, we propose a statistical meshless model based on fuzzy tissue classification and mechanical property assignment, and meshless (i.e., based on the unstructured cloud of points that do not form elements) solution method. Instead of hard segmentation that divides intracranial area into nonoverlapping, constituent regions we use statistical classification to get the fuzzy membership functions of tissue classes for each voxel. Material properties are assigned to integration points based on this soft classification. Verification example shows that the proposed model gives equivalent results—difference in computed brain deformations of at most 0.2 mm—to the finite element method (FEM) and can certainly be considered for use in future simulations. Based on this concept, patient-specific computational models can be more efficiently and robustly generated in the clinical workflow.
BibTeX: @bookchapter{2012janzhangmillerCBfMneuroimage, author = {Zhang, Johnny Y. and Joldes, Grand Roman and Wittek, Adam and Horton, Ashley and Warfield, Simon K. and Miller, Karol}, title = {Neuroimage as a Biomechanical Model: Toward New Computational Biomechanics of the Brain}, journal = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2012}, doi = {10.1007/978-1-4614-3172-5_4} }
An adaptive Dynamic Relaxation method for solving nonlinear finite element problems. Application to brain shift estimation. [Abstract]	Joldes, G.R., Wittek, A. and Miller, K.	2011	International Journal for Numerical Methods in Biomedical Engineering, vol. 27(2), pp. 173-185	article	[BibTeX] [PDF] [DOI]
Abstract: Dynamic Relaxation is an explicit method that can be used for computing the steady state solution for a discretised continuum mechanics problem. The convergence speed of the method depends on the accurate estimation of the parameters involved, which is especially difficult for nonlinear problems. In this paper we propose a completely adaptive Dynamic Relaxation method in which the parameters are updated during the iteration process, converging to their optimal values. We use the proposed method for computing intra-operative organ deformations using non-linear finite element models involving large deformations, nonlinear materials and contacts. The simulation results prove the accuracy and computational efficiency of the method. The proposed method is also very well suited for GPU implementation.
BibTeX: @article{2011febjoldesmillerIJNMBEadaptive, author = {Joldes, Grand Roman and Wittek, Adam and Miller, Karol}, title = {An adaptive Dynamic Relaxation method for solving nonlinear finite element problems. Application to brain shift estimation.}, journal = {International Journal for Numerical Methods in Biomedical Engineering}, year = {2011}, volume = {27}, number = {2}, pages = {173--185}, doi = {10.1002/cnm.1407} }
Real-Time Nonlinear Finite Element Computations on GPU: Handling of Different Element Types [Abstract]	Joldes, G.R., Wittek, A. and Miller, K.	2011	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: Application of biomechanical modeling techniques in the area of medical image analysis and surgical simulation implies two conflicting requirements: accurate results and high solution speeds. Accurate results can be obtained only by using appropriate models and solution algorithms. In our previous papers, we have presented algorithms and solution methods for performing accurate nonlinear finite element analysis of brain shift (which includes mixed mesh, different nonlinear material models, finite deformations and brain–skull contacts) in less than 5 s on a personal computer using a Graphics Processing Unit (GPU) for models having up to 50,000 degrees of freedom. In this chapter, we compare several approaches for implementing different element types on the GPU using the NVIDIA Compute Unified Device Architecture. Our results can be used as a guideline for selecting the best GPU implementation approach for finite element algorithms which require mixed meshes or even for meshless methods.
BibTeX: @bookchapter{2011janjoldesmillerCBfMreal, author = {Joldes, Grand R. and Wittek, Adam and Miller, Karol}, title = {Real-Time Nonlinear Finite Element Computations on GPU: Handling of Different Element Types}, journal = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2011}, doi = {10.1007/978-1-4419-9619-0_8} }
On the Effects of Model Complexity in Computing Brain Deformation for Image-Guided Neurosurgery [Abstract]	Ma, J., Wittek, A., Zwick, B., Joldes, G.R., Warfield, S.K. and Miller, K.	2011	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: Intra-operative images acquired during brain surgery do not provide sufficient detail to confidently locate brain internal structures that have been identified in high-resolution pre-operative images. However, the pre-operative images can be warped to the intra-operative position of brain using predicted deformation field. While craniotomy-induced brain shift deformation can be accurately computed using patient-specific finite element models in real-time, accurate segmentation and meshing of brain internal structures remains a time-consuming task. In this chapter, we conduct a parametric study to evaluate the sensitivity of the predicted brain shift deformation to model complexity, which includes the effects of disregarding the differences in properties between the parenchyma, tumour and ventricles and applying different approaches for representing the ventricles (as a very soft solid or cavity) to minimise segmentation and meshing effort for model generation. The results suggest that the difference in brain shift deformation predicted by models due to such variation is not significant. Segmentation of brain parenchyma and skull seems sufficient to build models that can accurately predict craniotomy-induced brain shift deformation.
BibTeX: @bookchapter{2011janmamillerCBfMeffects, author = {Ma, Jiajie and Wittek, Adam and Zwick, Benjamin and Joldes, Grand R. and Warfield, Simon K. and Miller, Karol}, title = {On the Effects of Model Complexity in Computing Brain Deformation for Image-Guided Neurosurgery}, journal = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2011}, doi = {10.1007/978-1-4419-9619-0_6} }
The Effects of Young’s Modulus on Predicting Prostate Deformation for MRI-Guided Interventions [Abstract]	McAnearney, S., Fedorov, A., Joldes, G.R., Hata, N., Tempany, C., Miller, K. and Wittek, A.	2011	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: Accuracy of image-guided prostate interventions can be improved by warping (i.e., nonrigid registration) of high-quality multimodal preoperative magnetic resonance images to the intraoperative prostate geometry. Patient-specific biomechanical models have been applied in several studies when predicting the prostate intraoperative deformations for such warping. Obtaining exact patient-specific information about the stress parameter (e.g., Young’s modulus) of the prostate peripheral zone (PZ) and central gland (CG) for such models remains an unsolved problem. In this study, we investigated the effects of ratio of Young’s modulus of the central gland ECG to the peripheral zone EPZ when predicting the prostate intraoperative deformation for ten cases of prostate brachytherapy. The patient-specific prostate models were implemented by means of the specialized nonlinear finite element procedures that utilize total Lagrangian formulation and explicit integration in time domain. The loading was defined by prescribing deformations on the prostate outer surface. The neo-Hookean hyperelastic constitutive model was applied to simulate the PZ and CG mechanical responses. The PZ to CG Young’s modulus ratio ECG:EPZ was varied between 1:1 (upper bound of the literature data) and 1:40 (lower bound of the literature data). The study indicates that the predicted prostate intraoperative deformations and results of the prostate MRIs nonrigid registration obtained using the predicted deformations depend very weakly on the ECG:EPZ ratio.
BibTeX: @bookchapter{2011janmcanearneywittekCBfMeffects, author = {McAnearney, Stephen and Fedorov, Andriy and Joldes, Grand R. and Hata, Nobuhiko and Tempany, Clare and Miller, Karol and Wittek, Adam}, title = {The Effects of Young’s Modulus on Predicting Prostate Deformation for MRI-Guided Interventions}, journal = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2011}, doi = {10.1007/978-1-4419-9619-0_5} }
Introduction [Abstract]	Miller, K.	2011	Biomechanics of the Brain, Springer	bookchapter	[BibTeX] [DOI]
Abstract: The mechanical properties of living tissues continue to be the major topic of ­biomechanical investigations. Over the years, a vast amount of knowledge about load-bearing tissues, such as bones, ligaments, muscles and other components of the musculoskeletal system, blood vessels (and blood), lungs, skin and hair, has been published in journals and books. The very soft tissues of organs whose role has little or nothing to do with transmitting mechanical loads had been, until recently, outside the scope of the mainstream biomechanical research. Extremely important organs such as the liver, kidneys, prostate and other abdominal organs, and ­especially the brain, had been largely neglected by biomechanics.
BibTeX: @bookchapter{2011janmillermillerBotBintroduction, author = {Miller, Karol}, title = {Introduction}, journal = {Biomechanics of the Brain}, publisher = {Springer}, year = {2011}, doi = {10.1007/978-1-4419-9997-9_1} }
Biomechanical Modeling of the Brain for Computer-Assisted Neurosurgery [Abstract]	Miller, K., Wittek, A. and Joldes, G.	2011	Biomechanics of the Brain, Springer	bookchapter	[BibTeX] [DOI]
Abstract: During neurosurgery, the brain significantly deforms. Despite the enormous complexity of the brain (see Chap. 2) many aspects of its response can be reasonably described in purely mechanical terms, such as displacements, strains and stresses. They can therefore be analyzed using established methods of continuum mechanics. In this chapter, we discuss approaches to biomechanical modeling of the brain from the perspective of two distinct applications: neurosurgical simulation and neuroimage registration in image-guided surgery. These two challenging applications are described below.1
BibTeX: @bookchapter{2011janmillerjoldesBotBbiomechanical, author = {Miller, K. and Wittek, A. and Joldes, G.}, title = {Biomechanical Modeling of the Brain for Computer-Assisted Neurosurgery}, journal = {Biomechanics of the Brain}, publisher = {Springer}, year = {2011}, doi = {10.1007/978-1-4419-9997-9_6} }
Computational Biomechanics of the Brain; Application to Neuroimage Registration [Abstract]	Miller, K., Wittek, A., Joldes, G., Ma, J. and Zwick, B.J.	2011	Neural Tissue Biomechanics, Springer	article	[BibTeX] [DOI]
Abstract: We present selected topics in the area of mathematical and numerical modelling of the brain biomechanics for brain image registration. We show how to describe registration in purely mechanical terms, such as displacements, strains and stresses and perform it using established methods of continuum mechanics. We advocate the use of fully non-linear theory of continuum mechanics. We discuss in some detail modelling geometry, boundary conditions, loading and material properties. We consider numerical problems such as the use of hexahedral and mixed hexahedral-tetrahedral meshes as well as meshless spatial discretisation schemes as well as the effects of model complexity on accuracy of brain deformation computation. We advocate the use of Total Lagrangian Formulation of both finite element and meshless methods together with explicit time-stepping procedures. We support our recommendations and conclusions with an example of the computation of the brain shift for intra-operative image registration.
BibTeX: @article{2011janmillerzwickNTBcomputational, author = {Miller, Karol and Wittek, Adam and Joldes, Grand and Ma, Jiajie and Zwick, Ben Jamin}, title = {Computational Biomechanics of the Brain; Application to Neuroimage Registration}, journal = {Neural Tissue Biomechanics}, publisher = {Springer}, year = {2011}, doi = {10.1007/8415_2011_80} }
Total Lagrangian Explicit Dynamics-Based Simulation of Tissue Tearing [Abstract]	Vemaganti, K., Joldes, G.R., Miller, K. and Wittek, A.	2011	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: This study presents an approach to modeling the tearing of tissue in two dimensions taking into account both material and geometrical nonlinearities. The approach is based on the total Lagrangian explicit dynamics (TLED) algorithm and realigns edges in the mesh along the path of the tear by node relocation. As such, no new elements are created during the propagation of the tear. The material is assumed to be isotropic, and the tearing criterion is based on the maximum node-averaged principal stress. Preliminary results show that the approach is capable of handling both isotropic and anisotropic tears.
BibTeX: @bookchapter{2011janvemagantiwittekCBfMtotal, author = {Vemaganti, Kumar and Joldes, Grand R. and Miller, Karol and Wittek, Adam}, title = {Total Lagrangian Explicit Dynamics-Based Simulation of Tissue Tearing}, journal = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2011}, doi = {10.1007/978-1-4419-9619-0_7} }
Computational Biomechanics for Medicine	Wittek, A. Nielsen, P.M. and Miller, K. (Eds)	2011	Springer Science+Business Media, LLC, New York, NY	book	[BibTeX] [DOI]
BibTeX: @book{2011wittekwittekcomputational, author = {Adam Wittek}, title = {Computational Biomechanics for Medicine}, publisher = {Springer Science+Business Media, LLC}, year = {2011}, doi = {10.1007/978-1-4419-9619-0} }
Algorithms for Computational Biomechanics of the Brain [Abstract]	Wittek, A., Joldes, G. and Miller, K.	2011	Biomechanics of the Brain, Springer	bookchapter	[BibTeX] [DOI]
Abstract: Modeling of the brain responses due to injury-causing transients and surgery is a problem of continuum mechanics that involves irregular geometry, complex loading and boundary conditions, non-linear materials, and large deformations (see Chaps. 5 and 6). Finding a solution for such a problem requires computational algorithms of non-linear continuum mechanics.
BibTeX: @bookchapter{2011janwittekmillerBotBalgorithms, author = {Wittek, A. and Joldes, G. and Miller, K.}, title = {Algorithms for Computational Biomechanics of the Brain}, journal = {Biomechanics of the Brain}, publisher = {Springer}, year = {2011}, doi = {10.1007/978-1-4419-9997-9_9} }
Letter to the editor: Current progress in patient-specific modeling by Neal and Kerckhoffs (2010). [Abstract]	Wittek, A. and Miller, K.	2011	Brief Bioinform, vol. 12(5), pp. 545-546	article	[BibTeX] [PDF] [DOI]
Abstract: A recent review article on 'Current progress in patient-specific modeling' in Briefings in Bioinformatics contains the statement summarizing the results of our previous study 'On the unimportance of constitutive models in computing brain deformation for image-guided surgery' published in Biomechanics and Modeling in Mechanobiology as confirmation of adequacy of linear elastic model for such computation. The purpose of this Letter to the Editor is to clarify this statement by informing the Readers of Briefings in Bioinformatics that our study indicates the following: (i) a simple linear elastic constitutive model for the brain tissue is sufficient when used with an appropriate finite deformation solution (i.e. geometrically non-linear analysis); and (ii) Linear analysis approach that assumes infinitesimally small brain deformations leads to unrealistic results.
BibTeX: @article{2011sepwittekmillerBBletter, author = {Wittek, Adam and Miller, Karol}, title = {Letter to the editor: Current progress in patient-specific modeling by Neal and Kerckhoffs (2010).}, journal = {Brief Bioinform}, year = {2011}, volume = {12}, number = {5}, pages = {545--546}, doi = {10.1093/bib/bbr046} }
Biomechanics of the Brain	Miller, K. (Ed.)	2011	Springer Science+Business Media, LLC, New York, NY	book	[BibTeX] [DOI]
BibTeX: @book{2011millermillerbiomechanics,, title = {Biomechanics of the Brain}, publisher = {Springer Science+Business Media, LLC}, year = {2011}, doi = {10.1007/978-1-4419-9997-9} }
Can Vascular Dynamics Cause Normal Pressure Hydrocephalus? [Abstract]	Dutta-Roy, T., Wittek, A. and Miller, K.	2010	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: This study investigated the hypothesis that changes in the brain vasculature system can explain the mechanics of normal pressure hydrocephalus (NPH) growth. A generic 3-D mesh of a healthy human brain was created. We used a fully non-linear (geometric, constitutive and boundary conditions) 3-D model of the brain parenchyma. The brain parenchyma was modelled as a nearly incompressible, single-phase continuum. A hyperelastic constitutive law and finite deformation theory described the deformations within the brain parenchyma. The brain vasculature system was modelled biomechanically by modifying the relaxed shear modulus according to the cardiac cycle to produce a time varying shear modulus. As no study currently exists on the effects of vasculature on brain parenchyma material properties, a parametric investigation was conducted by varying the brain parenchyma relaxed shear modulus. It is widely believed that no more than 1 mm of Hg (133.416 Pa) transmantle pressure difference is associated with NPH. Hence, we loaded the brain parenchyma with 1 mm of Hg transmantle pressure difference to investigate this suggestion. Fully non-linear, implicit, quasi-static finite element procedures in the time domain were used to obtain the deformation of the brain parenchyma and the ventricles. The results of the simulations showed that 1 mm of Hg (133.416 Pa) did not produce the clinical condition of NPH, even with brain vasculature effects taken into account. We conclude from our work that it is highly unlikely for a phenomenon, such as the brain vasculature effects due to the cardiac cycle, which occurs many times a minute to be able to influence an event such as NPH which presents itself over a time scale of hours to days. We further suggest that the hypothesis of a purely mechanical basis for NPH growth needs to be revised.
BibTeX: @bookchapter{2010jandutta-roymillercan, author = {Dutta-Roy, Tonmoy and Wittek, Adam and Miller, Karol}, title = {Can Vascular Dynamics Cause Normal Pressure Hydrocephalus?}, booktitle = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2010}, doi = {10.1007/978-1-4419-5874-7_8} }
A meshless Total Lagrangian explicit dynamics algorithm for surgical simulation	Horton, A., Wittek, A., Joldes, G.R. and Miller, K.	2010	International Journal for Numerical Methods in Biomedical Engineering, vol. 26(8), pp. 977-998, John Wiley & Sons, Ltd.	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2010hortonmillerIJfNMiBEmeshless, author = {Horton, Ashley and Wittek, Adam and Joldes, Grand Roman and Miller, Karol}, title = {A meshless Total Lagrangian explicit dynamics algorithm for surgical simulation}, journal = {International Journal for Numerical Methods in Biomedical Engineering}, publisher = {John Wiley & Sons, Ltd.}, year = {2010}, volume = {26}, number = {8}, pages = {977--998}, doi = {10.1002/cnm.1374} }
Cortical Surface Motion Estimation for Brain Shift Prediction [Abstract]	Joldes, G.R., Wittek, A. and Miller, K.	2010	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: In this chapter we present an algorithm for computing the displacement of the exposed surface of the brain during surgery. The motion of the cortical surface is recovered by registering the preoperative surface extracted from high-resolution MRI images to the intraoperative surface acquired during surgery. The recovered motion can then be used for driving a biomechanical model in order to predict the displacement of the internal brain structures, especially the tumor, which can be presented to the surgeon using an image-guided neurosurgery system. Our algorithm combines an image registration method with curvature information associated with the features of the brain surface to perform the non-rigid surface registration. The extracted displacement field can be used directly for driving a biomechanical model, as it does not include any implausible deformations. It also works in cases when the boundaries of the two registered surfaces are not identical, extracting the displacements only for the overlapping regions of the two surfaces. We tested the accuracy of the proposed algorithm using synthetically generated data as well as surfaces extracted from preoperative and intraoperative MRI images of the brain.
BibTeX: @bookchapter{2010janjoldesmillercortical, author = {Joldes, Grand Roman and Wittek, Adam and Miller, Karol}, title = {Cortical Surface Motion Estimation for Brain Shift Prediction}, booktitle = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2010}, doi = {10.1007/978-1-4419-5874-7_6} }
Real-Time Nonlinear Finite Element Computations on GPU - Application to Neurosurgical Simulation. [Abstract]	Joldes, G.R., Wittek, A. and Miller, K.	2010	Computer Methods in Applied Mechanics and Engineering, vol. 199(49-52), pp. 3305-3314	article	[BibTeX] [PDF] [DOI]
Abstract: Application of biomechanical modeling techniques in the area of medical image analysis and surgical simulation implies two conflicting requirements: accurate results and high solution speeds. Accurate results can be obtained only by using appropriate models and solution algorithms. In our previous papers we have presented algorithms and solution methods for performing accurate nonlinear finite element analysis of brain shift (which includes mixed mesh, different non-linear material models, finite deformations and brain-skull contacts) in less than a minute on a personal computer for models having up to 50.000 degrees of freedom. In this paper we present an implementation of our algorithms on a Graphics Processing Unit (GPU) using the new NVIDIA Compute Unified Device Architecture (CUDA) which leads to more than 20 times increase in the computation speed. This makes possible the use of meshes with more elements, which better represent the geometry, are easier to generate, and provide more accurate results.
BibTeX: @article{2010decjoldesmillerCMAMEreal, author = {Joldes, Grand Roman and Wittek, Adam and Miller, Karol}, title = {Real-Time Nonlinear Finite Element Computations on GPU - Application to Neurosurgical Simulation.}, journal = {Computer Methods in Applied Mechanics and Engineering}, school = {Intelligent Systems for Medicine Laboratory, School of Mechanical Engineering, The University of Western Australia, Perth, AUSTRALIA.}, year = {2010}, volume = {199}, number = {49-52}, pages = {3305--3314}, doi = {10.1016/j.cma.2010.06.037} }
Evaluation of accuracy of non-linear finite element computations for surgical simulation: study using brain phantom	Ma, J., Wittek, A., Singh, S., Joldes, G., Washio, T., Chinzei, K. and Miller, K.	2010	Computer methods in biomechanics and biomedical engineering, vol. 13(6), pp. 783-794, Taylor & Francis Group	article	[BibTeX] [DOI]
BibTeX: @article{2010mamillerCmibabeevaluation, author = {Ma, J and Wittek, A and Singh, S and Joldes, G and Washio, T and Chinzei, K and Miller, K}, title = {Evaluation of accuracy of non-linear finite element computations for surgical simulation: study using brain phantom}, journal = {Computer methods in biomechanics and biomedical engineering}, publisher = {Taylor & Francis Group}, year = {2010}, volume = {13}, number = {6}, pages = {783--794}, doi = {10.1080/10255841003628995} }
Accuracy of Non-linear FE Modelling for Surgical Simulation: Study Using Soft Tissue Phantom [Abstract]	Ma, J., Wittek, A., Singh, S., Joldes, G.R., Washio, T., Chinzei, K. and Miller, K.	2010	Computational Biomechanics for Medicine, Springer	bookchapter	[BibTeX] [DOI]
Abstract: In this chapter, we evaluated the accuracy of non-linear FE modelling in application to surgical simulation. We compared experiment and FE modelling of indentation of the soft tissue phantom. The evaluation was done in terms of soft tissue phantom deformation and the forces acting on the indenter. The soft tissue phantom deformation was measured by tracking 3D motions of X-ray opaque markers placed in the direct neighbourhood under the indenter with a custom-built bi-plane X-ray image intensifiers (XRII) system. The modelling of soft tissue phantom indentation was conducted using the ABAQUS/standard finite element solver. Specific constitutive properties of the soft tissue phantom determined through semi-confined uniaxial compression tests were used in the model. The model accurately predicted the indentation force–displacement relations and marker displacements. The agreement between modelling and experimental results verifies the reliability of our FE modelling techniques and confirms the predictive power of these techniques in surgical simulation.
BibTeX: @bookchapter{2010janmamilleraccuracy, author = {Ma, Jiajie and Wittek, Adam and Singh, Surya and Joldes, Grand Roman and Washio, Toshikatsu and Chinzei, Kiyoyuki and Miller, Karol}, title = {Accuracy of Non-linear FE Modelling for Surgical Simulation: Study Using Soft Tissue Phantom}, booktitle = {Computational Biomechanics for Medicine}, publisher = {Springer}, year = {2010}, doi = {10.1007/978-1-4419-5874-7_4} }
Computational Biomechanics for Medicine	Miller, K. Nielsen, P.M. (Ed.)	2010	Springer Science+Business Media, LLC, New York, NY	book	[BibTeX] [DOI]
BibTeX: @book{2010millermillercomputational, author = {Karol Miller}, title = {Computational Biomechanics for Medicine}, publisher = {Springer Science+Business Media, LLC}, year = {2010}, doi = {10.1007/978-1-4419-5874-7} }
Biomechanics of the brain for computer-integrated surgery. [Abstract]	Miller, K., Wittek, A. and Joldes, G.	2010	Acta of Bioengineering and Biomechanics, vol. 12(2), pp. 25-37	article	[BibTeX] [PDF]
Abstract: This article presents a summary of the key-note lecture delivered at Biomechanics 10 Conference held in August 2010 in Warsaw. We present selected topics in the area of mathematical and numerical modelling of the brain biomechanics for neurosurgical simulation and brain image registration. These processes can reasonably be described in purely mechanical terms, such as displacements, strains and stresses and therefore can be analysed using established methods of continuum mechanics. We advocate the use of fully non-linear theory of continuum mechanics. We discuss in some detail modelling geometry, boundary conditions, loading and material properties. We consider numerical problems such as the use of hexahedral and mixed hexahedral-tetrahedral meshes as well as meshless spatial discretisation schemes. We advocate the use of Total Lagrangian Formulation of both finite element and meshless methods together with explicit time-stepping procedures. We support our recommendations and conclusions with an example of brain shift computation for intraoperative image registration.
BibTeX: @article{2010millerjoldesABBbiomechanics, author = {Miller, Karol and Wittek, Adam and Joldes, Grand}, title = {Biomechanics of the brain for computer-integrated surgery.}, journal = {Acta of Bioengineering and Biomechanics}, school = {Intelligent Systems for Medicine Laboratory, School of Mechanical Engineering, The University of Western Australia, Crawley, Australia. [email protected]}, year = {2010}, volume = {12}, number = {2}, pages = {25--37} }
Modelling brain deformations for computer-integrated neurosurgery	Miller, K., Wittek, A., Joldes, G., Horton, A., Dutta-Roy, T., Berger, J. and Morriss, L.	2010	International Journal for Numerical Methods in Biomedical Engineering, vol. 26(1), pp. 117-138, Wiley Online Library	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2010millermorrissIJfNMiBEmodelling, author = {Miller, K and Wittek, A and Joldes, G and Horton, A and Dutta-Roy, T and Berger, J and Morriss, L}, title = {Modelling brain deformations for computer-integrated neurosurgery}, journal = {International Journal for Numerical Methods in Biomedical Engineering}, publisher = {Wiley Online Library}, year = {2010}, volume = {26}, number = {1}, pages = {117--138}, doi = {10.1002/cnm.1260} }
Patient-specific non-linear finite element modelling for predicting soft organ deformation in real-time: application to non-rigid neuroimage registration. [Abstract]	Wittek, A., Joldes, G., Couton, M., Warfield, S.K. and Miller, K.	2010	Progress in Biophysics and Molecular biology, vol. 103(2-3), pp. 292-303	article	[BibTeX] [PDF] [DOI]
Abstract: Long computation times of non-linear (i.e. accounting for geometric and material non-linearity) biomechanical models have been regarded as one of the key factors preventing application of such models in predicting organ deformation for image-guided surgery. This contribution presents real-time patient-specific computation of the deformation field within the brain for six cases of brain shift induced by craniotomy (i.e. surgical opening of the skull) using specialised non-linear finite element procedures implemented on a graphics processing unit (GPU). In contrast to commercial finite element codes that rely on an updated Lagrangian formulation and implicit integration in time domain for steady state solutions, our procedures utilise the total Lagrangian formulation with explicit time stepping and dynamic relaxation. We used patient-specific finite element meshes consisting of hexahedral and non-locking tetrahedral elements, together with realistic material properties for the brain tissue and appropriate contact conditions at the boundaries. The loading was defined by prescribing deformations on the brain surface under the craniotomy. Application of the computed deformation fields to register (i.e. align) the preoperative and intraoperative images indicated that the models very accurately predict the intraoperative deformations within the brain. For each case, computing the brain deformation field took less than 4 s using an NVIDIA Tesla C870 GPU, which is two orders of magnitude reduction in computation time in comparison to our previous study in which the brain deformation was predicted using a commercial finite element solver executed on a personal computer.
BibTeX: @article{2010decwittekmillerPBMBpatient, author = {Wittek, Adam and Joldes, Grand and Couton, Mathieu and Warfield, Simon K and Miller, Karol}, title = {Patient-specific non-linear finite element modelling for predicting soft organ deformation in real-time: application to non-rigid neuroimage registration.}, journal = {Progress in Biophysics and Molecular biology}, school = {Intelligent Systems for Medicine Laboratory, School of Mechanical and Chemical Engineering, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia. [email protected]}, year = {2010}, volume = {103}, number = {2-3}, pages = {292--303}, doi = {10.1016/j.pbiomolbio.2010.09.001} }
Real-Time Prediction of Brain Shift Using Nonlinear Finite Element Algorithms [Abstract]	Joldes, G.R., Wittek, A., Couton, M., Warfield, S.K. and Miller, K.	2009	Medical Image Computing and Computer-Assisted Intervention – MICCAI 2009, pp. 300-307, Springer	inproceedings	[BibTeX] [PDF] [DOI]
Abstract: Patient-specific biomechanical models implemented using specialized nonlinear (i.e. taking into account material and geometric nonlinearities) finite element procedures were applied to predict the deformation field within the brain for five cases of craniotomy-induced brain shift. The procedures utilize the Total Lagrangian formulation with explicit time stepping. The loading was defined by prescribing deformations on the brain surface under the craniotomy. Application of the computed deformation fields to register the preoperative images with the intraoperative ones indicated that the models very accurately predict the intraoperative positions and deformations of the brain anatomical structures for limited information about the brain surface deformations. For each case, it took less than 40 s to compute the deformation field using a standard personal computer, and less than 4 s using a Graphics Processing Unit (GPU). The results suggest that nonlinear biomechanical models can be regarded as one possible method of complementing medical image processing techniques when conducting non-rigid registration within the real-time constraints of neurosurgery.
BibTeX: @inproceedings{2009janjoldesmillerreal, author = {Joldes, Grand Roman and Wittek, Adam and Couton, Mathieu and Warfield, Simon K. and Miller, Karol}, title = {Real-Time Prediction of Brain Shift Using Nonlinear Finite Element Algorithms}, booktitle = {Medical Image Computing and Computer-Assisted Intervention – MICCAI 2009}, publisher = {Springer}, year = {2009}, pages = {300--307}, doi = {10.1007/978-3-642-04271-3_37} }
Computation of intra-operative brain shift using dynamic relaxation. [Abstract]	Joldes, G.R., Wittek, A. and Miller, K.	2009	Computer Methods in Applied Mechanics and Engineering, vol. 198(41), pp. 3313-3320	article	[BibTeX] [PDF] [DOI]
Abstract: Many researchers have proposed the use of biomechanical models for high accuracy soft organ non-rigid image registration, but one main problem in using comprehensive models is the long computation time required to obtain the solution. In this paper we propose to use the Total Lagrangian formulation of the Finite Element method together with Dynamic Relaxation for computing intra-operative organ deformations. We study the best ways of estimating the parameters involved and we propose a termination criteria that can be used in order to obtain fast results with prescribed accuracy. The simulation results prove the accuracy and computational efficiency of the method, even in cases involving large deformations, nonlinear materials and contacts.
BibTeX: @article{2009sepjoldesmillerCMAMEcomputation, author = {Joldes, Grand Roman and Wittek, Adam and Miller, Karol}, title = {Computation of intra-operative brain shift using dynamic relaxation.}, journal = {Computer Methods in Applied Mechanics and Engineering}, school = {Intelligent Systems for Medicine Laboratory, School of Mechanical Engineering, The University of Western Australia, Perth, AUSTRALIA, [email protected] , [email protected] , [email protected] }, year = {2009}, volume = {198}, number = {41}, pages = {3313--3320}, doi = {10.1016/j.cma.2009.06.012} }
Non-locking Tetrahedral Finite Element for Surgical Simulation. [Abstract]	Joldes, G.R., Wittek, A. and Miller, K.	2009	Communications in Numerical Methods in Engineering, vol. 25(7), pp. 827-836	article	[BibTeX] [PDF] [DOI]
Abstract: To obtain a very fast solution for finite element models used in surgical simulations low order elements such as the linear tetrahedron or the linear under-integrated hexahedron must be used. Automatic hexahedral mesh generation for complex geometries remains a challenging problem, and therefore tetrahedral or mixed meshes are often necessary. Unfortunately the standard formulation of the linear tetrahedral element exhibits volumetric locking in case of almost incompressible materials. In this paper we extend the average nodal pressure tetrahedral element proposed by Bonet and Burton for a better handling of multiple material interfaces. The new formulation can handle multiple materials in a uniform way, with better accuracy, while requiring only a small additional computation effort. We discuss some implementation issues and show how easy an existing TLED (Total Lagrangian Explicit Dynamics) algorithm can be modified in order to support the new element formulation. The performance evaluation of the new element shows the clear improvement in reaction forces and displacements predictions compared to the average nodal pressure element in case of models consisting of multiple materials.
BibTeX: @article{2009juljoldesmillerCNMEnon, author = {Joldes, Grand Roman and Wittek, Adam and Miller, Karol}, title = {Non-locking Tetrahedral Finite Element for Surgical Simulation.}, journal = {Communications in Numerical Methods in Engineering}, school = {Intelligent Systems for Medicine Laboratory, School of Mechanical Engineering, The University of Western Australia, 35 Stirling Highway, Crawley/Perth WA 6009, AUSTRALIA, , , https://www.mech.uwa.edu.au/ISML/}, year = {2009}, volume = {25}, number = {7}, pages = {827--836}, doi = {10.1002/cnm.1185} }
Suite of finite element algorithms for accurate computation of soft tissue deformation for surgical simulation. [Abstract]	Joldes, G.R., Wittek, A. and Miller, K.	2009	Medical Image Analysis, vol. 13(6), pp. 912-919, Elsevier	article	[BibTeX] [PDF] [DOI]
Abstract: Real time computation of soft tissue deformation is important for the use of augmented reality devices and for providing haptic feedback during operation or surgeon training. This requires algorithms that are fast, accurate and can handle material nonlinearities and large deformations. A set of such algorithms is presented in this paper, starting with the finite element formulation and the integration scheme used and addressing common problems such as hourglass control and locking. The computation examples presented prove that by using these algorithms, real time computations become possible without sacrificing the accuracy of the results. For a brain model having more than 7,000 degrees of freedom, we computed the reaction forces due to indentation with frequency of around 1,000 Hz using a standard dual core PC. Similarly, we conducted simulation of brain shift using a model with more than 50,000 degrees of freedom in less than one minute. The speed benefits of our models result from combining the Total Lagrangian formulation with explicit time integration and low order finite elements.
BibTeX: @article{2009decjoldesmillerMIAsuite, author = {Joldes, Grand Roman and Wittek, Adam and Miller, Karol}, title = {Suite of finite element algorithms for accurate computation of soft tissue deformation for surgical simulation.}, journal = {Medical Image Analysis}, publisher = {Elsevier}, school = {Intelligent Systems for Medicine Laboratory, School of Mechanical Engineering, The University of Western Australia, 35 Stirling Highway, Crawley/Perth, WA 6009, Australia. [email protected]}, year = {2009}, volume = {13}, number = {6}, pages = {912--919}, doi = {10.1016/j.media.2008.12.001} }
Special Section on Computational Biomechanics for Medicine	Miller, K.	2009	ELSEVIER SCIENCE BV PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS	book	[BibTeX]
BibTeX: @book{2009millermillerspecial, author = {Miller, Karol}, title = {Special Section on Computational Biomechanics for Medicine}, publisher = {ELSEVIER SCIENCE BV PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, year = {2009} }
The Computational Biomechanics for Medicine Workshop series.	Miller, K.	2009	Medical Image Analysis, vol. 13(6), pp. 911	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2009decmillermillerMIAcomputational, author = {Miller, Karol}, title = {The Computational Biomechanics for Medicine Workshop series.}, journal = {Medical Image Analysis}, school = {The University of Western Australia, School of Mechanical Engineering, 35 Stirling Highway, Crawley/Perth WA 6009, Australia.}, year = {2009}, volume = {13}, number = {6}, pages = {911}, doi = {10.1016/j.media.2008.10.002} }
On the unimportance of constitutive models in computing brain deformation for image-guided surgery [Abstract]	Wittek, A., Hawkins, T. and Miller, K.	2009	Biomechanics and Modeling in Mechanobiology, vol. 8(1), pp. 77, Springer	article	[BibTeX] [PDF] [DOI]
Abstract: Imaging modalities that can be used intra-operatively do not provide sufficient details to confidently locate the abnormalities and critical healthy areas that have been identified from high-resolution pre-operative scans. However, as we have shown in our previous work, high quality pre-operative images can be warped to the intra-operative position of the brain. This can be achieved by computing deformations within the brain using a biomechanical model. In this paper, using a previously developed patient-specific model of brain undergoing craniotomy-induced shift, we conduct a parametric analysis to investigate in detail the influences of constitutive models of the brain tissue. We conclude that the choice of the brain tissue constitutive model, when used with an appropriate finite deformation solution, does not affect the accuracy of computed displacements, and therefore a simple linear elastic model for the brain tissue is sufficient.
BibTeX: @article{2009febwittekmillerBaMiMunimportance, author = {Wittek, Adam and Hawkins, Trent and Miller, Karol}, title = {On the unimportance of constitutive models in computing brain deformation for image-guided surgery}, journal = {Biomechanics and Modeling in Mechanobiology}, publisher = {Springer}, year = {2009}, volume = {8}, number = {1}, pages = {77}, doi = {10.1007/s10237-008-0118-1} }
Coupling finite element and mesh-free methods for modelling brain defromations in response to tumour growth	Berger, J., Horton, A., Joldes, G., Wittek, A. and Miller, K.	2008	Computational Biomechanics for Medicine III MICCAI-Associated Workshop	bookchapter	[BibTeX] [PDF]
BibTeX: @bookchapter{2008bergermillerCBfMIMWcoupling, author = {Berger, J and Horton, A and Joldes, G and Wittek, A and Miller, K}, title = {Coupling finite element and mesh-free methods for modelling brain defromations in response to tumour growth}, journal = {Computational Biomechanics for Medicine III MICCAI-Associated Workshop}, year = {2008} }
Biomechanical modelling of normal pressure hydrocephalus. [Abstract]	Dutta-Roy, T., Wittek, A. and Miller, K.	2008	Journal of Biomechanics, vol. 41(10), pp. 2263-2271	article	[BibTeX] [PDF] [DOI]
Abstract: This study investigates the mechanics of normal pressure hydrocephalus (NPH) growth using a computational approach. We created a generic 3-D brain mesh of a healthy human brain and modelled the brain parenchyma as single phase and biphasic continuum. In our model, hyperelastic constitutive law and finite deformation theory described deformations within the brain parenchyma. We used a value of 155.77Pa for the shear modulus (mu) of the brain parenchyma. Additionally, in our model, contact boundary definitions constrained the brain outer surface inside the skull. We used transmantle pressure difference to load the model. Fully nonlinear, implicit finite element procedures in the time domain were used to obtain the deformations of the ventricles and the brain. To the best of our knowledge, this was the first 3-D, fully nonlinear model investigating NPH growth mechanics. Clinicians generally accept that at most 1mm of Hg transmantle pressure difference (133.416Pa) is associated with the condition of NPH. Our computations showed that transmantle pressure difference of 1mm of Hg (133.416Pa) did not produce NPH for either single phase or biphasic model of the brain parenchyma. A minimum transmantle pressure difference of 1.764mm of Hg (235.44Pa) was required to produce the clinical condition of NPH. This suggested that the hypothesis of a purely mechanical basis for NPH growth needs to be revised. We also showed that under equal transmantle pressure difference load, there were no significant differences between the computed ventricular volumes for biphasic and incompressible/nearly incompressible single phase model of the brain parenchyma. As a result, there was no major advantage gained by using a biphasic model for the brain parenchyma. We propose that for modelling NPH, nearly incompressible single phase model of the brain parenchyma was adequate. Single phase treatment of the brain parenchyma simplified the mathematical description of the NPH model and resulted in significant reduction of computational time.
BibTeX: @article{2008juldutta-roymillerJBbiomechanical, author = {Dutta-Roy, Tonmoy and Wittek, Adam and Miller, Karol}, title = {Biomechanical modelling of normal pressure hydrocephalus.}, journal = {Journal of Biomechanics}, school = {Intelligent Systems for Medicine Laboratory, School of Mechanical Engineering MBDP: M050, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. [email protected]}, year = {2008}, volume = {41}, number = {10}, pages = {2263--2271}, doi = {10.1016/j.jbiomech.2008.04.014} }
Realistic and efficient brain-skull interaction model for brain shift computation	Joldes, G., Wittek, A., Miller, K. and Morriss, L.	2008	Computational Biomechanics for Medicine III Workshop, MICCAI, pp. 95-105	bookchapter	[BibTeX]
BibTeX: @bookchapter{2008joldesmorrissCBfMIWMrealistic, author = {Joldes, GR and Wittek, A and Miller, K and Morriss, L}, title = {Realistic and efficient brain-skull interaction model for brain shift computation}, journal = {Computational Biomechanics for Medicine III Workshop, MICCAI}, year = {2008}, pages = {95--105} }
An efficient hourglass control implementation for the uniform strain hexahedron using the total Lagrangian formulation	Joldes, G.R., Wittek, A. and Miller, K.	2008	Communications in Numerical Methods in Engineering, vol. 24(11), pp. 1315-1323, Wiley Online Library	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2008joldesmillerCiNMiEefficient, author = {Joldes, Grand Roman and Wittek, Adam and Miller, Karol}, title = {An efficient hourglass control implementation for the uniform strain hexahedron using the total Lagrangian formulation}, journal = {Communications in Numerical Methods in Engineering}, publisher = {Wiley Online Library}, year = {2008}, volume = {24}, number = {11}, pages = {1315--1323}, doi = {10.1002/cnm.1034} }
Compression testing of very soft biological tissues using semi-confined configuration--a word of caution. [Abstract]	Morriss, L., Wittek, A. and Miller, K.	2008	Journal of Biomechanics, vol. 41(1), pp. 235-238	article	[BibTeX] [PDF] [DOI]
Abstract: We analyse semi-confined (i.e. using no-slip boundary conditions) compression experiment of very soft tissue sample using finite element method. We show that the assumption that the planes perpendicular to the direction of the applied force remain plane during the experiments is not satisfied for compression levels lower than previously stated in Miller [2005. Method for testing very soft biological tissues in compression. Journal of Biomechanics 38, 153-158]. Therefore, we recommend that the parameters for constitutive models of very soft tissues be determined by fitting a solution of the finite element models of the experimental set-up to the measurements obtained using semi-confined compression experiments.
BibTeX: @article{2008morrissmillerJBcompression, author = {Morriss, Leith and Wittek, Adam and Miller, Karol}, title = {Compression testing of very soft biological tissues using semi-confined configuration--a word of caution.}, journal = {Journal of Biomechanics}, school = {Intelligent Systems for Medicine Laboratory, School of Mechanical Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, Perth,WA 6009, Australia.}, year = {2008}, volume = {41}, number = {1}, pages = {235--238}, doi = {10.1016/j.jbiomech.2007.06.025} }
Confocal arthroscopic assessment of osteoarthritis in situ. [Abstract]	Smolinski, D., Jones, C.W., Wu, J.P., Miller, K., Kirk, T.B. and Zheng, M.H.	2008	Arthroscopy, vol. 24(4), pp. 423-429	article	[BibTeX] [PDF] [DOI]
Abstract: This study aimed to assess the ability of the laser scanning confocal arthroscope (LSCA) to evaluate cartilage microstructure, particularly in differentiating stages of human osteoarthritis (OA) as classified by the International Cartilage Repair Society (ICRS) OA grade definitions.Ten tibial plateaus from total knee arthroplasty patients were obtained at the time of surgery. Cartilage areas were visually graded based on the ICRS classification, imaged by use of a 7-mm-diameter LSCA (488-nm excitation with 0.5% [wt/vol] fluorescein, 20-minute staining period), and then removed with underlying bone for histologic examination with H&E staining. The 2 imaging techniques were then compared for each ICRS grade to ascertain similarity between the methods and thus gauge the techniques' diagnostic resolution. Cartilage surface degeneration was readily imaged and OA severity accurately gauged by the LSCA and confirmed by histology.LSCA and histologic images of specimens in the late stages of OA were seen to be mutually related even though they were imaged in planes that were orthogonal to each other. Useful and comparable diagnostic resolution was obtained in all imaged specimens from subjects with various stages of OA.This study showed the LSCA's ability to image detailed cartilage surface morphologic features that identify grade 1 through 4 of the ICRS OA grading system. The LSCA's imaging potential was best shown by its ability to resolve the fine collagen network present under the lamina splendens. The incorporation of high-magnification confocal technology within the confines of an arthroscopic probe has proved to provide the imaging requirements necessary to perform detailed cartilage condition assessment.In comparison to video arthroscopy, LSCA provides increased magnification along with improved contrast and resolution.
BibTeX: @article{2008aprsmolinskizhengAconfocal, author = {Smolinski, Daniel and Jones, Chris W and Wu, Jian P and Miller, Karol and Kirk, Thomas B and Zheng, Ming H}, title = {Confocal arthroscopic assessment of osteoarthritis in situ.}, journal = {Arthroscopy}, school = {School of Mechanical Engineering, University of Western Australia, Perth, Australia.}, year = {2008}, volume = {24}, number = {4}, pages = {423--429}, doi = {10.1016/j.arthro.2007.10.003} }
Subject-specific non-linear biomechanical model of needle insertion into brain	Wittek, A., Dutta-Roy, T., Taylor, Z., Horton, A., Washio, T., Chinzei, K. and Miller, K.	2008	Computer methods in biomechanics and biomedical engineering, vol. 11(2), pp. 135-146, Taylor & Francis Group	article	[BibTeX] [DOI]
BibTeX: @article{2008wittekmillerCmibabesubject, author = {Wittek, A and Dutta-Roy, T and Taylor, Z and Horton, A and Washio, T and Chinzei, K and Miller, K}, title = {Subject-specific non-linear biomechanical model of needle insertion into brain}, journal = {Computer methods in biomechanics and biomedical engineering}, publisher = {Taylor & Francis Group}, year = {2008}, volume = {11}, number = {2}, pages = {135--146}, doi = {10.1080/10255840701688095} }
3-D nonlinear FE analysis of normal pressure hydrocephalus	Dutta-Roy, T., Wittek, A. and Miller, K.	2007	Proceedings of Computational Biomechanics for Medicine Workshop, International Conference on Medical Image Computing and Computer-Assisted Intervention, pp. 94-102	inproceedings	[BibTeX]
BibTeX: @inproceedings{2007dutta-roymiller3, author = {Dutta-Roy, T. and Wittek, A. and Miller, K}, title = {3-D nonlinear FE analysis of normal pressure hydrocephalus}, booktitle = {Proceedings of Computational Biomechanics for Medicine Workshop, International Conference on Medical Image Computing and Computer-Assisted Intervention}, year = {2007}, pages = {94--102} }
Computer simulation of brain shift using an Element Free Galerkin method	Horton, A., Wittek, A. and Miller, K.	2007	Proceedings of 7th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering, pp. 906-911	inproceedings	[BibTeX]
BibTeX: @inproceedings{2007hortonmillercomputer, author = {Horton, A. and Wittek, A. and Miller, K.}, title = {Computer simulation of brain shift using an Element Free Galerkin method}, booktitle = {Proceedings of 7th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering}, year = {2007}, pages = {906--911} }
Subject-Specific Biomechanical Simulation of Brain Indentation Using a Meshless Method [Abstract]	Horton, A., Wittek, A. and Miller, K.	2007	Medical Image Computing and Computer-Assisted Intervention – MICCAI 2007, Springer	inproceedings	[BibTeX] [PDF] [DOI]
Abstract: We develop a meshless method for simulating soft organ deformation. The method is motivated by simple, automatic model creation for real-time simulation. Our method is meshless in the sense that deformation is calculated at nodes that are not part of an element mesh. Node placement is almost arbitrary. Fully geometrically nonlinear total Lagrangian formulation is used. Geometric integration is performed over a regular background grid that does not conform to the simulation geometry. Explicit time integration is used via the central difference method. To validate the method we simulate indentation of a swine brain and compare the results to experimental data.
BibTeX: @inproceedings{2007janhortonmillersubject, author = {Horton, Ashley and Wittek, Adam and Miller, Karol}, title = {Subject-Specific Biomechanical Simulation of Brain Indentation Using a Meshless Method}, booktitle = {Medical Image Computing and Computer-Assisted Intervention – MICCAI 2007}, publisher = {Springer}, year = {2007}, doi = {10.1007/978-3-540-75757-3_66} }
Towards non-linear finite element computations in real time	Joldes, G., Wittek, A. and Miller, K.	2007	Proceedings of 7th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering, pp. 894-899	inproceedings	[BibTeX]
BibTeX: @inproceedings{2007joldesmillertowards, author = {Joldes, G. and Wittek, A. and Miller, K.}, title = {Towards non-linear finite element computations in real time}, booktitle = {Proceedings of 7th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering}, year = {2007}, pages = {894--899} }
Suite of finite element algorithms for accurate computation of soft tissue deformation for surgical simulation	Joldes, G.R., Wittek, A. and Miller, K.	2007	Proceedings of Computational Biomechanics for Medicine Workshop, International Conference on Medical Image Computing and Computer-Assisted Intervention, pp. 65-73	inproceedings	[BibTeX] [PDF] [DOI]
BibTeX: @inproceedings{2007joldesmillersuite, author = {Joldes, G. R. and Wittek, A. and Miller, K}, title = {Suite of finite element algorithms for accurate computation of soft tissue deformation for surgical simulation}, booktitle = {Proceedings of Computational Biomechanics for Medicine Workshop, International Conference on Medical Image Computing and Computer-Assisted Intervention}, year = {2007}, pages = {65--73}, doi = {10.1016/j.media.2008.12.001} }
Linear versus non-linear computation of the brain shift	Miller, K., Hawkins, T. and Wittek, A.	2007	Proceedings of 7th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering, pp. 888-893	inproceedings	[BibTeX]
BibTeX: @inproceedings{2007millerwitteklinear, author = {Miller, K. and Hawkins, T. and Wittek, A.}, title = {Linear versus non-linear computation of the brain shift}, booktitle = {Proceedings of 7th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering}, year = {2007}, pages = {888--893} }
Total Lagrangian explicit dynamics finite element algorithm for computing soft tissue deformation	Miller, K., Joldes, G., Lance, D. and Wittek, A.	2007	Communications in numerical methods in engineering, vol. 23(2), pp. 121-134, Wiley Online Library	article	[BibTeX] [PDF]
BibTeX: @article{2007millerwittekCinmietotal, author = {Miller, Karol and Joldes, Grand and Lance, Dane and Wittek, Adam}, title = {Total Lagrangian explicit dynamics finite element algorithm for computing soft tissue deformation}, journal = {Communications in numerical methods in engineering}, publisher = {Wiley Online Library}, year = {2007}, volume = {23}, number = {2}, pages = {121--134} }
Confocal arthroscopy-based patient-specific constitutive models of cartilaginous tissues - II: prediction of reaction force history of meniscal cartilage specimens. [Abstract]	Taylor, Z.A., Kirk, T.B. and Miller, K.	2007	Computer methods in biomechanics and biomedical engineering, vol. 10(5), pp. 327-336	article	[BibTeX] [DOI]
Abstract: The theoretical framework developed in a companion paper (Part I) is used to derive estimates of mechanical response of two meniscal cartilage specimens. The previously developed framework consisted of a constitutive model capable of incorporating confocal image-derived tissue microstructural data. In the present paper (Part II) fibre and matrix constitutive parameters are first estimated from mechanical testing of a batch of specimens similar to, but independent from those under consideration. Image analysis techniques which allow estimation of tissue microstructural parameters form confocal images are presented. The constitutive model and image-derived structural parameters are then used to predict the reaction force history of the two meniscal specimens subjected to partially confined compression. The predictions are made on the basis of the specimens' individual structural condition as assessed by confocal microscopy and involve no tuning of material parameters. Although the model does not reproduce all features of the experimental curves, as an unfitted estimate of mechanical response the prediction is quite accurate. In light of the obtained results it is judged that more general non-invasive estimation of tissue mechanical properties is possible using the developed framework.
BibTeX: @article{2007octtaylormillerCMBBEconfocal, author = {Taylor, Zeike A and Kirk, Thomas B and Miller, Karol}, title = {Confocal arthroscopy-based patient-specific constitutive models of cartilaginous tissues - II: prediction of reaction force history of meniscal cartilage specimens.}, journal = {Computer methods in biomechanics and biomedical engineering}, school = {Intelligent Systems for Medicine Laboratory, School of Mechanical Engineering, The University of Western Australia, Perth, WA, Australia.}, year = {2007}, volume = {10}, number = {5}, pages = {327--336}, doi = {10.1080/10255840701336828} }
Patient-specific model of brain deformation: application to medical image registration. [Abstract]	Wittek, A., Miller, K., Kikinis, R. and Warfield, S.K.	2007	Journal of Biomechanics, vol. 40(4), pp. 919-929, Elsevier	article	[BibTeX] [PDF] [DOI]
Abstract: This contribution presents finite element computation of the deformation field within the brain during craniotomy-induced brain shift. The results were used to illustrate the capabilities of non-linear (i.e. accounting for both geometric and material non-linearities) finite element analysis in non-rigid registration of pre- and intra-operative magnetic resonance images of the brain. We used patient-specific hexahedron-dominant finite element mesh, together with realistic material properties for the brain tissue and appropriate contact conditions at boundaries. The model was loaded by the enforced motion of nodes (i.e. through prescribed motion of a boundary) at the brain surface in the craniotomy area. We suggest using explicit time-integration scheme for discretised equations of motion, as the computational times are much shorter and accuracy, for practical purposes, the same as in the case of implicit integration schemes. Application of the computed deformation field to register (i.e. align) the pre-operative images with the intra-operative ones indicated that the model very accurately predicts the displacements of the tumour and the lateral ventricles even for limited information about the brain surface deformation. The prediction accuracy improves when information about deformation of not only exposed (during craniotomy) but also unexposed parts of the brain surface is used when prescribing loading. However, it appears that the accuracy achieved using information only about the deformation of the exposed surface, that can be determined without intra-operative imaging, is acceptable. The presented results show that non-linear biomechanical models can complement medical image processing techniques when conducting non-rigid registration. Important advantage of such models over the previously used linear ones is that they do not require unrealistic assumptions that brain deformations are infinitesimally small and brain stress-strain relationship is linear.
BibTeX: @article{2007wittekwarfieldJBpatient, author = {Wittek, Adam and Miller, Karol and Kikinis, Ron and Warfield, Simon K}, title = {Patient-specific model of brain deformation: application to medical image registration.}, journal = {Journal of Biomechanics}, publisher = {Elsevier}, school = {Intelligent Systems for Medicine Laboratory, School of Mechanical Engineering, The University of Western Australia, 35 Stirling Highway, Crawley/Perth, WA 6009, Australia.}, year = {2007}, volume = {40}, number = {4}, pages = {919--929}, doi = {10.1016/j.jbiomech.2006.02.021} }
Towards Realistic Surgical Simulation: Biomechanics of Needle Insertion into the Brain [Abstract]	Dutta-Roy, T., Wittek, A., Taylor, Z., Chinzei, K., Washio, T. and Miller, K.	2006	Romansy 16, Springer	inproceedings	[BibTeX] [DOI]
Abstract: Robotic surgery has been recognised in the past few years to have immense potential. Understanding the biomechanics of surgical procedures is central to robotic surgery. Needle insertion into soft tissues is a common surgical procedure but the biomechanics of needle insertion is poorly understood. We developed a computational biomechanical model to understand the mechanics of needle insertion into the brain tissue. The brain tissue is considered as a single phase continuum undergoing finite deformations. A non-linear constitutive model of the brain tissue is used. Precise geometrical model of the brain is obtained from MRI images and the brain mesh is created. The brain computational model is verified by comparing with previously published experimental results for porcine brain indentation. The reaction forces acting on the needle during insertion are obtained using fully non-linear, explicit Finite Element procedures in time domain.
BibTeX: @inproceedings{2006jandutta-roymillerR1towards, author = {Dutta-Roy, Tonmoy and Wittek, Adam and Taylor, Zeike and Chinzei, Kiyoyuki and Washio, Toshikatsu and Miller, Karol}, title = {Towards Realistic Surgical Simulation: Biomechanics of Needle Insertion into the Brain}, booktitle = {Romansy 16}, publisher = {Springer}, year = {2006}, doi = {10.1007/3-211-38927-X_38} }
Comparison of constitutive models of brain tissue for non-rigid image registration	Hawkins, T., Wittek, A. and Miller, K.	2006	2nd Workshop on Computer Assisted Diagnosis and Surgery	inproceedings	[BibTeX] [PDF]
BibTeX: @inproceedings{2006hawkinsmiller2WoCADaScomparison, author = {Hawkins, Trent and Wittek, Adam and Miller, Karol}, title = {Comparison of constitutive models of brain tissue for non-rigid image registration}, booktitle = {2nd Workshop on Computer Assisted Diagnosis and Surgery}, year = {2006} }
Towards meshless methods for surgical simulation	Horton, A., Wittek, A. and Miller, K.	2006	Computational Biomechanics for Medicine Workshop, Medical Image Computing and Computer-Assisted Intervention MICCAI, pp. 34-42	bookchapter	[BibTeX] [PDF]
BibTeX: @bookchapter{2006hortonmillerCBfMWMICaCIMtowards, author = {Horton, Ashley and Wittek, Adam and Miller, Karol}, title = {Towards meshless methods for surgical simulation}, journal = {Computational Biomechanics for Medicine Workshop, Medical Image Computing and Computer-Assisted Intervention MICCAI}, year = {2006}, pages = {34--42} }
Improved linear tetrahedral element for surgical simulation	Joldes, G.R., Wittek, A. and Miller, K.	2006	Medical Image Computing and Computer-Assisted Intervention, vol. 1(2006), pp. 54-65	inproceedings	[BibTeX] [PDF]
BibTeX: @inproceedings{2006joldesmillerPMimproved, author = {Joldes, Grand Roman and Wittek, Adam and Miller, Karol}, title = {Improved linear tetrahedral element for surgical simulation}, booktitle = {Medical Image Computing and Computer-Assisted Intervention}, year = {2006}, volume = {1}, number = {2006}, pages = {54--65} }
New finite element algorithm for surgical simulation	Miller, K., Joldes, G. and Wittek, A.	2006	2nd Workshop on Computer Assisted Diagnosis and Surgery	inproceedings	[BibTeX] [PDF]
BibTeX: @inproceedings{2006millerwittek2WoCADaSnew, author = {Miller, Karol and Joldes, Grand and Wittek, Adam}, title = {New finite element algorithm for surgical simulation}, booktitle = {2nd Workshop on Computer Assisted Diagnosis and Surgery}, year = {2006} }
Neuroimage registration as displacement-zero traction problem of solid mechanics	Miller, K. and Wittek, A.	2006	COMPUTATIONAL BIOMECHANICS FOR MEDICINE, pp. 2	bookchapter	[BibTeX] [PDF]
BibTeX: @bookchapter{2006millerwittekCBFMneuroimage, author = {Miller, Karol and Wittek, Adam}, title = {Neuroimage registration as displacement-zero traction problem of solid mechanics}, journal = {COMPUTATIONAL BIOMECHANICS FOR MEDICINE}, year = {2006}, pages = {2} }
Numerical analysis of maximal bat performance in baseball. [Abstract]	Nicholls, R.L., Miller, K. and Elliott, B.C.	2006	Journal of Biomechanics, vol. 39(6), pp. 1001-1009, Elsevier	article	[BibTeX] [PDF] [DOI]
Abstract: Metal baseball bats have been experimentally demonstrated to produce higher ball exit velocity (BEV) than wooden bats. In the United States, all bats are subject to BEV tests using hitting machines that rotate the bat in a horizontal plane. In this paper, a model of bat-ball impact was developed based on 3-D translational and rotational kinematics of a swing performed by high-level players. The model was designed to simulate the maximal performance of specific models of a wooden bat and a metal bat when swung by a player, and included material properties and kinematics specific to each bat. Impact dynamics were quantified using the finite element method (ANSYS/LSDYNA, version 6.1). Maximum BEV from both a metal (61.5 m/s) and a wooden (50.9 m/s) bat exceeded the 43.1 m/s threshold by which bats are certified as appropriate for commercial sale. The lower BEV from the wooden bat was attributed to a lower pre-impact bat linear velocity, and a more oblique impact that resulted in a greater proportion of BEV being lost to lateral and vertical motion. The results demonstrate the importance of factoring bat linear velocity and spatial orientation into tests of maximal bat performance, and have implications for the design of metal baseball bats.
BibTeX: @article{2006nichollselliottJBnumerical, author = {Nicholls, Rochelle L and Miller, Karol and Elliott, Bruce C}, title = {Numerical analysis of maximal bat performance in baseball.}, journal = {Journal of Biomechanics}, publisher = {Elsevier}, school = {School of Mechanical Engineering, The University of Western Australia, Crawley, Perth, Western Australia 6009, Australia.}, year = {2006}, volume = {39}, number = {6}, pages = {1001--1009}, doi = {10.1016/j.jbiomech.2005.02.020} }
Constitutive modeling of cartilaginous tissues: a review. [Abstract]	Taylor, Z.A. and Miller, K.	2006	Journal of Applied Biomechanics, vol. 22(3), pp. 212-229	article	[BibTeX] [PDF]
Abstract: An important and longstanding field of research in orthopedic biomechanics is the elucidation and mathematical modeling of the mechanical response of cartilaginous tissues. Traditional approaches have treated such tissues as continua and have described their mechanical response in terms of macroscopic models borrowed from solid mechanics. The most important of such models are the biphasic and single-phase viscoelastic models, and the many variations thereof. These models have reached a high level of maturity and have been successful in describing a wide range of phenomena. An alternative approach that has received considerable recent interest, both in orthopedic biomechanics and in other fields, is the description of mechanical response based on consideration of a tissue's structure--so-called microstructural modeling. Examples of microstructurally based approaches include fibril-reinforced biphasic models and homogenization approaches. A review of both macroscopic and microstructural constitutive models is given in the present work.
BibTeX: @article{2006augtaylormillerJABconstitutive, author = {Taylor, Zeike A and Miller, Karol}, title = {Constitutive modeling of cartilaginous tissues: a review.}, journal = {Journal of Applied Biomechanics}, school = {Intelligent Systems for Medicine Laboratgory, School of Mechanical Engineering, University of Western Australia, Crawley/Perth WA, Australia.}, year = {2006}, volume = {22}, number = {3}, pages = {212--229} }
Development of confocal image-based patient-specific models of cartilaginous tissues	Taylor, Z., Kirk, T. and Miller, K.	2006	Proceedings of 7th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering, pp. 846-851	inproceedings	[BibTeX]
BibTeX: @inproceedings{2006taylormillerdevelopment, author = {Taylor, ZA and Kirk, TB and Miller, K}, title = {Development of confocal image-based patient-specific models of cartilaginous tissues}, booktitle = {Proceedings of 7th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering}, year = {2006}, pages = {846--851} }
Quantitative characterization of collagen orientation in the superficial zone for studying early degenerative changes in articular cartilage	Wu, J., Kirk, T., Peng, Z., Miller, K. and Zheng, M.	2006	Journal of musculoskeletal research, vol. 10(01), pp. 1-12, World Scientific Publishing Company	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2006wuzhengJomrquantitative, author = {Wu, JP and Kirk, TB and Peng, Z and Miller, K and Zheng, MH}, title = {Quantitative characterization of collagen orientation in the superficial zone for studying early degenerative changes in articular cartilage}, journal = {Journal of musculoskeletal research}, publisher = {World Scientific Publishing Company}, year = {2006}, volume = {10}, number = {01}, pages = {1--12}, doi = {10.1142/S0218957706001674} }
Method of testing very soft biological tissues in compression. [Abstract]	Miller, K.	2005	Journal of Biomechanics, vol. 38(1), pp. 153-158, Elsevier	article	[BibTeX] [PDF] [DOI]
Abstract: Mechanical properties of very soft tissues, such as brain, liver, kidney and prostate have recently joined the mainstream research topics in biomechanics. This has happened in spite of the fact that these tissues do not bear mechanical loads. The interest in the biomechanics of very soft tissues has been motivated by the developments in computer-integrated and robot-aided surgery--in particular, the emergence of automatic surgical tools and robots-as well as advances in virtual reality techniques. Mechanical testing of very soft tissues provides a formidable challenge for an experimenter. Very soft tissues are usually tested in compression using an unconfined compression set-up, which requires ascertaining that friction between sample faces and stress-strain machine platens is close to zero. In this paper a more reliable method of testing is proposed. In the proposed method top and bottom faces of a cylindrical specimen with low aspect ratio are rigidly attached to the platens of the stress-strain machine (e.g. using surgical glue). This arrangement allows using a no-slip boundary condition in the analysis of the results. Even though the state of deformation in the sample cannot be treated as orthogonal the relationships between total change of height (measured) and strain are obtained. Two important results are derived: (i) deformed shape of a cylindrical sample subjected to uniaxial compression is independent on the form of constitutive law, (ii) vertical extension in the plane of symmetry lambda(z) is proportional to the total change of height for strains as large as 30%. The importance and relevance of these results to testing procedures in biomechanics are highlighted.
BibTeX: @article{2005janmillermillerJBmethod, author = {Miller, Karol}, title = {Method of testing very soft biological tissues in compression.}, journal = {Journal of Biomechanics}, publisher = {Elsevier}, school = {School of Mechanical Engineering, The University of Western Australia, 35 Stirling Highway, Crawley/Perth WA 6009, Australia. [email protected]}, year = {2005}, volume = {38}, number = {1}, pages = {153--158}, doi = {10.1016/j.jbiomech.2004.03.004} }
Most recent results in the biomechanics of the brain.	Miller, K.	2005	Journal of Biomechanics, vol. 38(4), pp. 965; author reply 967, 969	article	[BibTeX] [PDF] [DOI]
BibTeX: @article{2005aprmillermillerJBmost, author = {Miller, Karol}, title = {Most recent results in the biomechanics of the brain.}, journal = {Journal of Biomechanics}, year = {2005}, volume = {38}, number = {4}, pages = {965; author reply 967, 969}, doi = {10.1016/j.jbiomech.2004.03.032} }
Modeling of Brain Mechanical Properties for Computer-Integrated Medicine [Abstract]	Miller, K. and Nowinski, W.L.	2005	Robotics Research. The Eleventh International Symposium, Springer	bookchapter	[BibTeX] [DOI]
Abstract: Many modern applications of technology to medicine, such as robotic surgery, non-rigid registration, virtual reality operation planning and surgeon training systems, and surgical simulators, require knowledge of mechanical properties of very soft tissues. In this paper we describe and identify a model of mechanical properties of brain tissue aimed in particular at integration with interactive brain atlases. A non-linear, viscoelastic model based on the generalization of the Ogden strain energy hyperelastic constitutive equation is proposed. The material parameters are identified using in-vivo experimental results. The model accounts well for brain tissue deformation behavior in both tension and compression (natural strain ε〈 − 0.3, 0.2〉 ) for strain rates typical for surgical procedures. It can be immediately applied in large-scale finite element simulations and, therefore, offers the possibility of incorporating mechanics into surgical planning and training systems such as NeuroPlanner and BrainBench. Finally we show that the brain model identified based on in-vivo experiments can be applied in the more realistic in-vivo setting.
BibTeX: @bookchapter{2005janmillernowinskiRRTEISmodeling, author = {Miller, Karol and Nowinski, Wieslaw L.}, title = {Modeling of Brain Mechanical Properties for Computer-Integrated Medicine}, journal = {Robotics Research. The Eleventh International Symposium}, publisher = {Springer}, year = {2005}, doi = {10.1007/11008941_14} }
Towards computing brain deformations for diagnosis, prognosis and neurosurgical simulation	Miller, K., Taylor, Z. and Nowinski, W.L.	2005	Journal of Mechanics in Medicine and Biology, vol. 5(01), pp. 105-121, World Scientific Publishing Company	article	[BibTeX] [PDF]
BibTeX: @article{2005millernowinskiJoMiMaBtowards, author = {Miller, Karol and Taylor, Zeike and Nowinski, Wieslaw L}, title = {Towards computing brain deformations for diagnosis, prognosis and neurosurgical simulation}, journal = {Journal of Mechanics in Medicine and Biology}, publisher = {World Scientific Publishing Company}, year = {2005}, volume = {5}, number = {01}, pages = {105--121} }
A numerical model for risk of ball-impact injury to baseball pitchers. [Abstract]	Nicholls, R.L., Miller, K. and Elliott, B.C.	2005	Medicine & Science in Sports & Exercise, vol. 37(1), pp. 30-38	article	[BibTeX] [PDF]
Abstract: Metal baseball bats produce higher ball exit velocity (BEV) than wood bats, increasing the risk of impact injuries to infield players. In this paper, maximum BEV from a wood and a metal bat were determined using the finite element method.Three-dimensional (3-D) bat kinematics at the instant of impact were determined from high-speed videography (N = 17 high-performance batters). A linear viscoelastic constitutive model was developed for stiffer and softer types of baseballs. The risk of impact injury was determined using available movement time data for adult pitchers; the data indicate that 0.400 s is required to evade a batted ball.The highest BEV (61.5 m.s(-1)) was obtained from the metal bat and the stiffer ball model, equating to 0.282 s of available movement time. For five impacts along the long axis of each bat, the "best case scenario" resulted from the wood bat and the softer ball (46.0 m.s(-1), 0.377 s).The performance difference between the bats was attributed to the preimpact linear velocity of the bat impact point and to differences in orientation on the horizontal plane. Reducing the swing moment of the baseball bat, and the shear and relaxation modulii of the baseball, increased the available movement time.
BibTeX: @article{2005jannichollselliottMSSEnumerical, author = {Nicholls, Rochelle L and Miller, Karol and Elliott, Bruce C}, title = {A numerical model for risk of ball-impact injury to baseball pitchers.}, journal = {Medicine & Science in Sports & Exercise}, school = {School of Mechanical Engineering, The University of Western Australia, Crawley, Perth, Western Australia, Australia. [email protected]}, year = {2005}, volume = {37}, number = {1}, pages = {30--38} }
Modeling deformation behavior of the baseball. [Abstract]	Nicholls, R.L., Miller, K. and Elliott, B.C.	2005	Journal of Applied Biomechanics, vol. 21(1), pp. 18-30	article	[BibTeX] [PDF]
Abstract: Regulating ball response to impact is one way to control ball exit velocity in baseball. This is necessary to reduce injuries to defensive players and maintain the balance between offense and defense in the game. This paper presents a model for baseball velocity-dependent behavior. Force-displacement data were obtained using quasi-static compression tests to 50% of ball diameter (n = 70 baseballs). The force-displacement curves for a very stiff baseball (Model B) and a softer type (Model C) were characterized by a Mooney-Rivlin model using implicit finite element analysis (ANSYS software, version 6.1). Agreement between experimental and numerical results was excellent for both Model B (C(10) = 0, C(01) = 3.7e(6) Pa) and Model C (C(10) = 0, C(01) = 2.6e(6) Pa). However, this material model was not available in the ANSYS/LSDYNA explicit dynamic software (version 6.1) used to quantify the transient behavior of the ball. Therefore the modeling process was begun again using a linear viscoelastic material. G(infinity), the long-term shear modulus of the material, was determined by the same implicit FEA procedure. Explicit FEA was used to quantify the time-dependent response of each ball in terms of instantaneous shear modulus (G0) and a decay term (beta). The results were evaluated with respect to published experimental data for the ball coefficient of restitution at five velocities (13.4-40.2 ms(-1)) and were in agreement with the experimental values. The model forms the basis for future research on baseball response to impact with the bat.
BibTeX: @article{2005febnichollselliottJABmodeling, author = {Nicholls, Rochelle Llewelyn and Miller, Karol and Elliott, Bruce C}, title = {Modeling deformation behavior of the baseball.}, journal = {Journal of Applied Biomechanics}, school = {School of Mechanical Engineering, The University of Western Australia, Perth.}, year = {2005}, volume = {21}, number = {1}, pages = {18--30} }
Using numerical approximation as an intermediate step in analytical derivations: some observations from biomechanics. [Abstract]	Taylor, Z. and Miller, K.	2005	Journal of Biomechanics, vol. 38(12), pp. 2497-2502	article	[BibTeX] [PDF] [DOI]
Abstract: We present four examples to illustrate the use of a type of numerical approximation as an intermediate step in analytical derivation of seemingly complicated biomechanical equations. The method involves examination of curve shapes to elucidate useful underlying trends, which may otherwise be overlooked through consideration of only the equations themselves. Two examples of the method's use are drawn from recently published results in the area of experimental methods in biomechanics of very soft tissues, and two others are taken from our current work on cartilage tissue mechanics. We think that such observations provide a useful means of circumventing complexity issues when deriving models for biomechanical analysis, and further that the method, while simple in concept, could be effective in a range of biomechanics applications.
BibTeX: @article{2005dectaylormillerJBusing, author = {Taylor, Zeike and Miller, Karol}, title = {Using numerical approximation as an intermediate step in analytical derivations: some observations from biomechanics.}, journal = {Journal of Biomechanics}, school = {Intelligent Systems for Medicine Laboratory, School of Mechanical Engineering, The University of Western Australia, 35 Stirling Highway, Crawley/Perth WA 6009, Australia.}, year = {2005}, volume = {38}, number = {12}, pages = {2497--2502}, doi = {10.1016/j.jbiomech.2004.10.007} }
Brain Shift Computation Using a Fully Nonlinear Biomechanical Model [Abstract]	Wittek, A., Kikinis, R., Warfield, S.K. and Miller, K.	2005	Medical Image Computing and Computer-Assisted Intervention – MICCAI 2005, Springer	inproceedings	[BibTeX] [PDF] [DOI]
Abstract: In the present study, fully nonlinear (i.e. accounting for both geometric and material nonlinearities) patient specific finite element brain model was applied to predict deformation field within the brain during the craniotomy-induced brain shift. Deformation of brain surface was used as displacement boundary conditions. Application of the computed deformation field to align (i.e. register) the preoperative images with the intraoperative ones indicated that the model very accurately predicts the displacements of gravity centers of the lateral ventricles and tumor even for very limited information about the brain surface deformation. These results are sufficient to suggest that nonlinear biomechanical models can be regarded as one possible way of complementing medical image processing techniques when conducting nonrigid registration. Important advantage of such models over the linear ones is that they do not require unrealistic assumptions that brain deformations are infinitesimally small and brain tissue stress–strain relationship is linear.
BibTeX: @inproceedings{2005janwittekmillerbrain, author = {Wittek, Adam and Kikinis, Ron and Warfield, Simon K. and Miller, Karol}, title = {Brain Shift Computation Using a Fully Nonlinear Biomechanical Model}, booktitle = {Medical Image Computing and Computer-Assisted Intervention – MICCAI 2005}, publisher = {Springer}, year = {2005}, doi = {10.1007/11566489_72} }
Utilization of two-dimensional fast Fourier transform and power spectral analysis for assessment of early degeneration of articular cartilage	Wu, J., Kirk, T., Peng, Z., Miller, K. and Zheng, M.	2005	Journal of Musculoskeletal Research, vol. 9(03), pp. 119-131, World Scientific Publishing Company	article	[BibTeX] [PDF]
BibTeX: @article{2005wuzhengJoMRutilization, author = {Wu, JP and Kirk, TB and Peng, Z and Miller, K and Zheng, MH}, title = {Utilization of two-dimensional fast Fourier transform and power spectral analysis for assessment of early degeneration of articular cartilage}, journal = {Journal of Musculoskeletal Research}, publisher = {World Scientific Publishing Company}, year = {2005}, volume = {9}, number = {03}, pages = {119--131} }
DEVELOPMENT OF A CONFOCAL ARTHROSCOPE FOR NON-INVASIVE HISTOLOGICAL ASSESSMENT OF CARTILAGE	Zheng, M., Willers, C., Wood, D., Jones, C., Smolinski, D., Wu, J., Miller, K. and Kirk, T.	2005	Journal of Bone & Joint Surgery, British Volume, vol. 87(SUPP III), pp. 347-347, British Editorial Society of Bone and Joint Surgery	article	[BibTeX]
BibTeX: @article{2005zhengkirkJoBJSBVdevelopment, author = {Zheng, MH and Willers, C and Wood, DJ and Jones, CW and Smolinski, D and Wu, JP and Miller, K and Kirk, TB}, title = {DEVELOPMENT OF A CONFOCAL ARTHROSCOPE FOR NON-INVASIVE HISTOLOGICAL ASSESSMENT OF CARTILAGE}, journal = {Journal of Bone & Joint Surgery, British Volume}, publisher = {British Editorial Society of Bone and Joint Surgery}, year = {2005}, volume = {87}, number = {SUPP III}, pages = {347--347} }
Quantification of chondrocyte morphology by confocal arthroscopy	Jones, C., Smolinski, D., Wu, J., Willers, C., Miller, K., Kirk, T. and Zheng, M.	2004	Journal of Musculoskeletal Research, vol. 8(04), pp. 145-154, World Scientific	article	[BibTeX] [PDF]
BibTeX: @article{2004joneszhengJoMRquantification, author = {Jones, CW and Smolinski, D and Wu, JP and Willers, C and Miller, K and Kirk, TB and Zheng, MH}, title = {Quantification of chondrocyte morphology by confocal arthroscopy}, journal = {Journal of Musculoskeletal Research}, publisher = {World Scientific}, year = {2004}, volume = {8}, number = {04}, pages = {145--154} }
Modeling of flow system dynamics	Miller, A., Badyda, K., Dyjas, J. and Miller, K.	2004	Journal of Thermal Science, vol. 13(1), pp. 56-61, Science Press	article	[BibTeX] [PDF]
BibTeX: @article{2004millermillerJoTSmodeling, author = {Miller, Andrzej and Badyda, Krzysztof and Dyjas, Jaroslaw and Miller, Karol}, title = {Modeling of flow system dynamics}, journal = {Journal of Thermal Science}, publisher = {Science Press}, year = {2004}, volume = {13}, number = {1}, pages = {56--61} }
Biomechanics without mechanics: calculating soft tissue deformation without differential equations of equilibrium	Miller, K.	2004	Computer Methods in Biomechanics and Biomedical Engineering Conference, pp. 1-8	inproceedings	[BibTeX]
BibTeX: @inproceedings{2004millermillerbiomechanics, author = {Miller, K.}, title = {Biomechanics without mechanics: calculating soft tissue deformation without differential equations of equilibrium}, booktitle = {Computer Methods in Biomechanics and Biomedical Engineering Conference}, year = {2004}, pages = {1--8} }
Optimal design and modeling of spatial parallel manipulators	Miller, K.	2004	The International Journal of Robotics Research, vol. 23(2), pp. 127-140, SAGE Publications	article	[BibTeX] [PDF]
BibTeX: @article{2004millermillerTIJoRRoptimal, author = {Miller, Karol}, title = {Optimal design and modeling of spatial parallel manipulators}, journal = {The International Journal of Robotics Research}, publisher = {SAGE Publications}, year = {2004}, volume = {23}, number = {2}, pages = {127--140} }
Impact Injuries in Baseball [Abstract]	Nicholls, R.L., Elliott, B.C. and Miller, K.	2004	Sports Medicine, vol. 34(1), pp. 17, Springer	article	[BibTeX] [PDF] [DOI]
Abstract: Baseball has one of the highest impact injury rates of all sports. These injuries are primarily attributed to impact by a ball after it has been hit, pitched or thrown. This paper will review the incidence and causal factors for impact injuries in baseball. Attention is given to the design and material properties of bats, in light of evidence suggesting balls hit into the infield from metal bats can reach velocities potentially lethal to defensive players. The distribution of bat mass along the long axis of the implement appears a major factor in the greater performance potential of metal bats over wooden bats of equal length and mass. The dynamic behaviour of baseballs has also been implicated in the severity of head and chest injuries experienced by players. Balls of greatly reduced stiffness have been introduced for junior play, but debate still remains over their performance and impact characteristics. The behaviour of the ball during high-speed impact with the bat has been the subject of relatively limited research, and the effect of manipulating baseball material properties to decrease batted-ball velocity is unclear. The value of batting helmets is evident in the observed reduction of head injuries in baseball, but the use of protective vests to decrease the incidence and severity of cardio-thoracic trauma appears to be contraindicated.
BibTeX: @article{2004jannichollsmillerSMimpact, author = {Nicholls, Rochelle L. and Elliott, Bruce C. and Miller, Karol}, title = {Impact Injuries in Baseball}, journal = {Sports Medicine}, publisher = {Springer}, year = {2004}, volume = {34}, number = {1}, pages = {17}, doi = {10.2165/00007256-200434010-00003} }
Reassessment of brain elasticity for analysis of biomechanisms of hydrocephalus. [Abstract]	Taylor, Z. and Miller, K.	2004	Journal of Biomechanics, vol. 37(8), pp. 1263-1269	article	[BibTeX] [PDF] [DOI]
Abstract: This paper presents results from a finite element study of the biomechanics of hydrocephalus, with special emphasis on a reassessment of the parenchyma elastic modulus. A two-dimensional finite element model of the human brain/ventricular system is developed and analysed under hydrocephalic loading conditions. It is shown that the Young's modulus of the brain parenchyma used in previous studies (3000-10000 Pa) corresponds to strain rates much higher than those present in hydrocephalic brains. Consideration of the brain's viscoelasticity leads to the derivation of a considerably lower modulus value of approximately 584 Pa.
BibTeX: @article{2004augtaylormillerJBreassessment, author = {Taylor, Zeike and Miller, Karol}, title = {Reassessment of brain elasticity for analysis of biomechanisms of hydrocephalus.}, journal = {Journal of Biomechanics}, school = {School of Mechanical and Materials Engineering, The University of Western Australia, 35 Stirling Highway, Crawley/Perth, WA 6009, Australia.}, year = {2004}, volume = {37}, number = {8}, pages = {1263--1269}, doi = {10.1016/j.jbiomech.2003.11.027} }
Computing reaction forces on surgical tools for robotic neurosurgery and surgical simulation	Wittek, A., Miller, K., Laporte, J., Kikinis, R. and Warfield, S.K.	2004	Proc. of Australasian Conference on Robotics and Automation ACRA, Canberra, Australia, pp. 1-8	inproceedings	[BibTeX] [PDF]
BibTeX: @inproceedings{2004wittekwarfieldPoACoRaAACAcomputing, author = {Wittek, Adam and Miller, K and Laporte, J and Kikinis, Ron and Warfield, Simon K}, title = {Computing reaction forces on surgical tools for robotic neurosurgery and surgical simulation}, booktitle = {Proc. of Australasian Conference on Robotics and Automation ACRA, Canberra, Australia}, year = {2004}, pages = {1--8} }
Biomechanics of brain for computer assisted surgery	Miller, K.	2003	Zeszyty Naukowe Katedry Mechaniki Stosowanej/Politechnika Śląska(20), pp. 309-314	article	[BibTeX]
BibTeX: @article{2003millermillerZNKMSbiomechanics, author = {Miller, K}, title = {Biomechanics of brain for computer assisted surgery}, journal = {Zeszyty Naukowe Katedry Mechaniki Stosowanej/Politechnika Śląska}, year = {2003}, number = {20}, pages = {309--314} }
Design and Applications of Parallel Robots [Abstract]	Miller, K.	2003	Robotics Research, Springer	bookchapter	[BibTeX] [DOI]
Abstract: An optimal kinematic design method suited for parallel manipulators is described. The optimal configuration for a Delta-type three-degree-of-freedom spatial, translational manipulator, known as the New University of Western Australia Robot (NUWAR) is presented, and shown to be advantageous over the Delta configuration in terms of workspace volume. These results led to the construction of a prototype and an Australian Patent application.The kinematic optimisation process yielding a design, which delivers the best compromise between manipulability and a new performance index: space utilisation, is presented. The process leading to finding an optimal configuration of Linear Delta robot is described.An example medical application of a parallel robot is discussed. The robot is designed to work inside an open magnetic resonance scanner. A concept of a robot control system, based on biomechanical models of organs the robot operates on, is presented.
BibTeX: @bookchapter{2003janmillermillerRRdesign, author = {Miller, Karol}, title = {Design and Applications of Parallel Robots}, journal = {Robotics Research}, publisher = {Springer}, year = {2003}, doi = {10.1007/3-540-36460-9_11} }
Bat kinematics in baseball: implications for ball exit velocity and player safety	Nicholls, R.L., Elliott, B.C., Miller, K. and Koh, M.	2003	Journal of Applied Biomechanics, vol. 19(4), pp. 283-294, HUMAN KINETICS PUBLISHERS, INC.	article	[BibTeX] [PDF]
BibTeX: @article{2003nichollskohJoABbat, author = {Nicholls, Rochelle L and Elliott, Bruce C and Miller, Karol and Koh, Michael}, title = {Bat kinematics in baseball: implications for ball exit velocity and player safety}, journal = {Journal of Applied Biomechanics}, publisher = {HUMAN KINETICS PUBLISHERS, INC.}, year = {2003}, volume = {19}, number = {4}, pages = {283--294} }
Evolutionary Algorithm for Robot Task Space Optimisation	Petitt, J. and Miller, K.	2003	11th World Congress in Mechanism and Machine Science, pp. 2046-2050	inproceedings	[BibTeX] [PDF]
BibTeX: @inproceedings{2003petittmiller1WCiMaMSevolutionary, author = {Petitt, J and Miller, Karol}, title = {Evolutionary Algorithm for Robot Task Space Optimisation}, booktitle = {11th World Congress in Mechanism and Machine Science}, year = {2003}, pages = {2046--2050} }
Optimal kinematic design of spatial parallel manipulators: application to linear delta robot	Stock, M. and Miller, K.	2003	Journal of Mechanical Design, vol. 125(2), pp. 292-301, American Society of Mechanical Engineers	article	[BibTeX] [PDF]
BibTeX: @article{2003stockmillerJoMDoptimal, author = {Stock, Michael and Miller, Karol}, title = {Optimal kinematic design of spatial parallel manipulators: application to linear delta robot}, journal = {Journal of Mechanical Design}, publisher = {American Society of Mechanical Engineers}, year = {2003}, volume = {125}, number = {2}, pages = {292--301} }
Microstructural modelling of articular cartilage using 3D confocal endoscopy	Taylor, Z.A., Miller, K. and Kirk, T.B.	2003	International Society of Biomechanics XIXth Congress: the human body in motion, 6-11 July, 2003, Dunedin, New Zealand, pp. 386-386, University of Otago	inproceedings	[BibTeX]
BibTeX: @inproceedings{2003taylorkirkISoBXCthbim6J2DNZmicrostructural, author = {Taylor, Zeike A and Miller, Karol and Kirk, Thomas B}, title = {Microstructural modelling of articular cartilage using 3D confocal endoscopy}, booktitle = {International Society of Biomechanics XIXth Congress: the human body in motion, 6-11 July, 2003, Dunedin, New Zealand}, publisher = {University of Otago}, year = {2003}, pages = {386--386} }
Brain mechanics For neurosurgery: modeling issues [Abstract]	Kyriacou, S.K., Mohamed, A., Miller, K. and Neff, S.	2002	Biomechanics and Modeling in Mechanobiology, vol. 1(2), pp. 151, Springer	article	[BibTeX] [PDF] [DOI]
Abstract:  Brain biomechanics has been investigated for more than 30 years. In particular, finite element analyses and other powerful computational methods have long been used to provide quantitative results in the investigation of dynamic processes such as head trauma. Nevertheless, the potential of these methods to simulate and predict the outcome of quasi-static processes such as neurosurgical procedures and neuropathological processes has only recently been explored. Some inherent difficulties in modeling brain tissues, which have impeded progress, are discussed in this work. The behavior of viscoelastic and poroelastic constitutive models is compared in simple 1-D simulations using the ABAQUS finite element platform. In addition, the behaviors of quasi-static brain constitutive models that have recently been proposed are compared. We conclude that a compressible viscoelastic solid model may be the most appropriate for modeling neurosurgical procedures.
BibTeX: @article{2002octkyriacouneffBaMiMbrain, author = {Kyriacou, Stelios K. and Mohamed, Ashraf and Miller, Karol and Neff, Samuel}, title = {Brain mechanics For neurosurgery: modeling issues}, journal = {Biomechanics and Modeling in Mechanobiology}, publisher = {Springer}, year = {2002}, volume = {1}, number = {2}, pages = {151}, doi = {10.1007/s10237-002-0013-0} }
Biomechanics of brain for computer integrated surgery	Miller, K.	2002	Warsaw University of Technology Publishing House Warsaw, Poland	book	[BibTeX]
BibTeX: @book{2002millermillerbiomechanics, author = {Miller, Karol}, title = {Biomechanics of brain for computer integrated surgery}, publisher = {Warsaw University of Technology Publishing House Warsaw, Poland}, year = {2002} }
Maximization of workspace volume of 3-DOF spatial parallel manipulators	Miller, K.	2002	Journal of mechanical design, vol. 124(2), pp. 347-350, American Society of Mechanical Engineers	article	[BibTeX] [PDF]
BibTeX: @article{2002millermillerJomdmaximization, author = {Miller, Karol}, title = {Maximization of workspace volume of 3-DOF spatial parallel manipulators}, journal = {Journal of mechanical design}, publisher = {American Society of Mechanical Engineers}, year = {2002}, volume = {124}, number = {2}, pages = {347--350} }
Mechanical properties of brain tissue in tension. [Abstract]	Miller, K. and Chinzei, K.	2002	Journal of Biomechanics, vol. 35(4), pp. 483-490, Elsevier	article	[BibTeX] [PDF]
Abstract: This paper contains experimental results of in vitro, uniaxial tension of swine brain tissue in finite deformation as well as proposes a new hyper-viscoelastic constitutive model for the brain tissue. The experimental results obtained for two loading velocities, corresponding to strain rates of 0.64 and 0.64 x 10(-2)s(-1), are presented. We believe that these are the first ever experiments of this kind. The applied strain rates were similar to those applied in our previous study, focused on explaining brain tissue properties in compression. The stress-strain curves are convex downward for all extension rates. The tissue response stiffened as the loading speed increased, indicating a strong stress-strain rate dependence. Swine brain tissue was found to be considerably softer in extension than in compression. Previously proposed in the literature brain tissue constitutive models, developed based on experimental data collected in compression are shown to be inadequate to explain tissue behaviour in tension. A new, non-linear, viscoelastic model based on the generalisation of the Ogden strain energy hyper-elastic constitutive equation is proposed. The new model accounts well for brain tissue deformation behaviour in both tension and compression (natural strain in <-0.3,0.2>) for strain rates ranging over five orders of magnitude.
BibTeX: @article{2002aprmillerchinzeiJBmechanical, author = {Miller, Karol and Chinzei, Kiyoyuki}, title = {Mechanical properties of brain tissue in tension.}, journal = {Journal of Biomechanics}, publisher = {Elsevier}, school = {Department of Mechanical and Materials Engineering, The University of Western Australia, Nedlands/Perth, WA 6907, Perth, Australia. [email protected]}, year = {2002}, volume = {35}, number = {4}, pages = {483--490} }
IMPACT BEHAVIOUR OF THE BASEBALL WITH IMPLICATIONS FOR PLAYER SAFETY	Nicholls, R.L., Miller, K. and Elliott, B.	2002	ISBS-Conference Proceedings Archive, vol. 1(1)	inproceedings	[BibTeX] [PDF]
BibTeX: @inproceedings{2002nichollselliottIPAimpact, author = {Nicholls, Rochelle Llewelyn and Miller, Karol and Elliott, Bruce}, title = {IMPACT BEHAVIOUR OF THE BASEBALL WITH IMPLICATIONS FOR PLAYER SAFETY}, booktitle = {ISBS-Conference Proceedings Archive}, year = {2002}, volume = {1}, number = {1} }
Six-dimensional visualisation of end-effector pose using colour spaces	Petitt, J.D. and Miller, K.	2002	Proc. 2002 Australasian Conference on Robotics and Automation, vol. 27, pp. 29	inproceedings	[BibTeX] [PDF]
BibTeX: @inproceedings{2002petittmillerP2ACoRaAsix, author = {Petitt, Joshua D and Miller, Karol}, title = {Six-dimensional visualisation of end-effector pose using colour spaces}, booktitle = {Proc. 2002 Australasian Conference on Robotics and Automation}, year = {2002}, volume = {27}, pages = {29} }
Design of Linear Delta Robot: Compromise Between Manipulability and Workspace Size [Abstract]	Stock, M. and Miller, K.	2002	Romansy 14, Springer	inproceedings	[BibTeX] [DOI]
Abstract: An optimal kinematic design method suited for parallel manipulators is developed. The kinematic optimization process yields a design, which delivers the best compromise between manipulability and a new performance index, space utilization. It is shown that the exhaustive search minimization algorithm is effective for as many as four independent design variables and presents a viable alternative to advanced non-linear programming methods. The manipulability generally exhibits relatively little variation when compared to space utilization. The tendency exists for the solution to converge on a zero workspace size architecture when manipulability is optimized alone. The inclusion of the space utilization index in the cost function is crucial for obtaining realistic design candidates.
BibTeX: @inproceedings{2002janstockmillerR1design, author = {Stock, Michael and Miller, Karol}, title = {Design of Linear Delta Robot: Compromise Between Manipulability and Workspace Size}, booktitle = {Romansy 14}, publisher = {Springer}, year = {2002}, doi = {10.1007/978-3-7091-2552-6_42} }
Significance of strain rate-dependence in modelling of organic materials	Taylor, Z. and Miller, K.	2002	Proc. 7th Int. Conf. Control, Automation, Robotics and Vision ICARCV 2002, vol. 1, pp. 408-412 vol.1	inproceedings	[BibTeX] [PDF] [DOI]
BibTeX: @inproceedings{2002dectaylormillersignificance, author = {Z. Taylor and K. Miller}, title = {Significance of strain rate-dependence in modelling of organic materials}, booktitle = {Proc. 7th Int. Conf. Control, Automation, Robotics and Vision ICARCV 2002}, year = {2002}, volume = {1}, pages = {408--412 vol.1}, doi = {10.1109/ICARCV.2002.1234856} }
MRI guided surgical robot	Chinzei, K. and Miller, K.	2001	Australian Conference on Robotics and Automation, Sydney, Australia, Nov, pp. 50-55	inproceedings	[BibTeX]
BibTeX: @inproceedings{2001chinzeimillermri, author = {Chinzei, Kiyoyuki and Miller, Karol}, title = {MRI guided surgical robot}, booktitle = {Australian Conference on Robotics and Automation, Sydney, Australia, Nov}, year = {2001}, pages = {50--55} }
Towards MRI guided surgical manipulator	Chinzei, K., Miller, K. and others	2001	Medical science monitor, vol. 7(1), pp. 153-163, MEDICAL SCIENCE INTERNATIONAL PUBLISHING	article	[BibTeX]
BibTeX: @article{2001chinzeiothersMsmtowards, author = {Chinzei, Kiyoyuki and Miller, Karol and others}, title = {Towards MRI guided surgical manipulator}, journal = {Medical science monitor}, publisher = {MEDICAL SCIENCE INTERNATIONAL PUBLISHING}, year = {2001}, volume = {7}, number = {1}, pages = {153--163} }
How to test very soft biological tissues in extension?	Miller, K.	2001	Journal of Biomechanics, vol. 34(5), pp. 651-657, Elsevier	article	[BibTeX] [DOI]
BibTeX: @article{2001millermillerJoBhow, author = {Miller, Karol}, title = {How to test very soft biological tissues in extension?}, journal = {Journal of Biomechanics}, publisher = {Elsevier}, year = {2001}, volume = {34}, number = {5}, pages = {651--657}, doi = {10.1016/S0021-9290(00)00236-0} }
Biomechanics of soft tissues	Miller, K.	2000	Medical Science Monitor, vol. 6(1), pp. MT158-MT167, International Scientific Information, Inc.	article	[BibTeX]
BibTeX: @article{2000millermillerMSMbiomechanics, author = {Miller, Karol}, title = {Biomechanics of soft tissues}, journal = {Medical Science Monitor}, publisher = {International Scientific Information, Inc.}, year = {2000}, volume = {6}, number = {1}, pages = {MT158--MT167} }
Constitutive modelling of abdominal organs	Miller, K.	2000	Journal of Biomechanics, vol. 33(3), pp. 367-373, Elsevier	article	[BibTeX]
BibTeX: @article{2000millermillerJobconstitutive, author = {Miller, Karol}, title = {Constitutive modelling of abdominal organs}, journal = {Journal of Biomechanics}, publisher = {Elsevier}, year = {2000}, volume = {33}, number = {3}, pages = {367--373} }
Mechanics of the New UWA Robot [Abstract]	Miller, K.	2000	Romansy 13, Springer	inproceedings	[BibTeX] [DOI]
Abstract: New University of Western Australia Robot is a variation of the well-known Delta parallel robot. Parallel manipulators possess a number of advantages when compared to traditional serial arms. They offer generally much higher rigidity and smaller mobile mass than their serial counterparts. These features allow much faster and more precise manipulations. The main disadvantage of parallel robots is their small workspace in comparison to serial arms of similar size. Our previous work investigated the influence of motor axes orientation on the workspace volume of Delta type manipulators. This research has shown that the Delta configuration is not optimal and that the configuration characterized by &#x03B1;=arcTan( 1/ 2 )&#x2248;35.26 ]]
BibTeX: @inproceedings{2000janmillermillerR1mechanics, author = {Miller, Karol}, title = {Mechanics of the New UWA Robot}, booktitle = {Romansy 13}, publisher = {Springer}, year = {2000}, doi = {10.1007/978-3-7091-2498-7_6} }
Non-linear computer simulation of brain deformation.	Miller, K.	2000	Biomedical sciences instrumentation, vol. 37, pp. 179-184	article	[BibTeX]
BibTeX: @article{2000millermillerBsinon, author = {Miller, K}, title = {Non-linear computer simulation of brain deformation.}, journal = {Biomedical sciences instrumentation}, year = {2000}, volume = {37}, pages = {179--184} }
Mechanical properties of brain tissue in-vivo: experiment and computer simulation	Miller, K., Chinzei, K., Orssengo, G. and Bednarz, P.	2000	Journal of Biomechanics, vol. 33(11), pp. 1369-1376, Elsevier	article	[BibTeX] [DOI]
BibTeX: @article{2000millerbednarzJobmechanical, author = {Miller, Karol and Chinzei, Kiyoyuki and Orssengo, Girma and Bednarz, Piotr}, title = {Mechanical properties of brain tissue in-vivo: experiment and computer simulation}, journal = {Journal of Biomechanics}, publisher = {Elsevier}, year = {2000}, volume = {33}, number = {11}, pages = {1369--1376}, doi = {10.1016/S0021-9290(00)00120-2} }
Constitutive model of brain tissue suitable for finite element analysis of surgical procedures	Miller, K.	1999	Journal of Biomechanics, vol. 32(5), pp. 531-537, Elsevier	article	[BibTeX]
BibTeX: @article{1999millermillerJobconstitutive, author = {Miller, Karol}, title = {Constitutive model of brain tissue suitable for finite element analysis of surgical procedures}, journal = {Journal of Biomechanics}, publisher = {Elsevier}, year = {1999}, volume = {32}, number = {5}, pages = {531--537} }
Which assessment type should be encouraged in professional degree courses--continuous, project-based or final examination-based	Miller, K.	1999	Teaching in the Disciplines/Learning in Context, pp. 278-281	inproceedings	[BibTeX]
BibTeX: @inproceedings{1999millermillerTitDiCwhich, author = {Miller, Karol}, title = {Which assessment type should be encouraged in professional degree courses--continuous, project-based or final examination-based}, booktitle = {Teaching in the Disciplines/Learning in Context}, year = {1999}, pages = {278--281} }
New UWA robot--possible application to robotic surgery.	Miller, K. and Chinzei, K.	1999	Biomedical sciences instrumentation, vol. 36, pp. 135-140	article	[BibTeX]
BibTeX: @article{1999millerchinzeiBsinew, author = {Miller, K and Chinzei, K}, title = {New UWA robot--possible application to robotic surgery.}, journal = {Biomedical sciences instrumentation}, year = {1999}, volume = {36}, pages = {135--140} }
Modelling soft tissue using biphasic theory—a word of caution	MILLER, K.	1998	Computer methods in biomechanics and biomedical engineering, vol. 1(3), pp. 261-263, Taylor & Francis Group	article	[BibTeX] [DOI]
BibTeX: @article{1998millermillerCMIBABMEmodelling, author = {MILLER, KAROL}, title = {Modelling soft tissue using biphasic theory—a word of caution}, journal = {Computer methods in biomechanics and biomedical engineering}, publisher = {Taylor & Francis Group}, year = {1998}, volume = {1}, number = {3}, pages = {261--263}, doi = {10.1080/01495739808936706} }
Constitutive modelling of brain tissue: experiment and theory	Miller, K. and Chinzei, K.	1997	Journal of Biomechanics, vol. 30(11), pp. 1115-1121, Elsevier	article	[BibTeX] [DOI]
BibTeX: @article{1997millerchinzeiJobconstitutive, author = {Miller, Karol and Chinzei, Kiyoyuki}, title = {Constitutive modelling of brain tissue: experiment and theory}, journal = {Journal of Biomechanics}, publisher = {Elsevier}, year = {1997}, volume = {30}, number = {11}, pages = {1115--1121}, doi = {10.1016/S0021-9290(97)00092-4} }
Experimental verification of modeling of DELTA robot dynamics by direct application of Hamilton's principle	Miller, K.	1995	Proc. Conf. IEEE Int Robotics and Automation, vol. 1, pp. 532-537 vol.1	inproceedings	[BibTeX] [DOI]
BibTeX: @inproceedings{1995maymillermillerexperimental, author = {K. Miller}, title = {Experimental verification of modeling of DELTA robot dynamics by direct application of Hamilton's principle}, booktitle = {Proc. Conf. IEEE Int Robotics and Automation}, year = {1995}, volume = {1}, pages = {532--537 vol.1}, doi = {10.1109/ROBOT.1995.525338} }

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